Homing Crystal Soulmass, a spell that surrounds your character with orbs that attack anything that gets too close to you. The breaking comes in that the Soulmasses are incredibly powerful if your magic stat is high enough and all five orbs hit. Only one sorcery is more powerful and it only has 4 castings as opposed to Homing Crystal Soulmass's 10. With an Intelligence stat of 50 and the most powerful catalyst in your possession, the spell can wipe the floor with every end-game boss in just a few castings. It and its downgraded version are also the only offensive sorceries that can be accurate without targeting, helping immensely with invading players who wear the Ring of Fog, although a patch reduced the range at which the Soulmasses trigger against such an opponent.
Lightning Weapons do considerable damage of a type that most armor provides little protection against and require no stat investment past whatever is needed to wield the weapon. These characteristics make them the preferred weapon type for low-level invaders, as well as players who prefer investing heavily on other stats.
Wrath Of The Gods, a shockwave miracle that has next to no start-up, does huge damage and is nearly guaranteed to stunlock opponents who stack poise (players using light armor don't suffer nearly as bad because they get blasted off their feet with invincible recovery frames on the first shockwave).
High Poise armor can be this against players using lighter weapons such as daggers.
On the other end of the spectrum, using the Wolf Ring and high poise armor often becomes a survival tactic in multiplayer due to the sheer amount of weapons that can stunlock opponents at 52 poise and below in a single hit (greatswords and even basic hammers come to mind...). The Claymore in particular is a heavy offender, since it blends high damage with the right stats, is lighter than most weapons of its category, and swings fairly fast. Unless you know when and how to get out of a stunlock, you're going to have a hard time fighting an opponent who knows just how good those weapons are.
Tranquil Walk Of Peace, a miracle slowing enemy movement speed to a crawl. Was pretty much universally hated before its nerf — now it's lamented how useless its reduced range makes it. The Stone Greatsword produces the same effect, and it's made even worse since it's a weapon with fairly fast swings and high stunlocking potential.
All of the Black Knight weapons have a ridiculously broken aspect in one way or another, with the common one being additional damage against demons (this turns nearly every Lost Izalith enemy into cannon fodder, in addition to several early bosses who become mooks later on) and excellent strength scaling. To wit:
The Sword; obtainable early on, high damage for its weight and requirements, and, like other weapons of its category, swiftly kills players that underestimate its power and are not used to breaking out of a stunlock.
The Greatsword; also obtainable early on, immense raw power, and some of the most intimidating movesets which incorporate launching opponents in the air. Don't let its slow swing speed fool you: the moment you get hit by it, expect your health to drop really fast.
The Greataxe; while it's obtained far later than its brethren, it's extremely powerful, and it swings much faster than other axes, allowing for quick combos that stun enemies before they can break out of it. If that wasn't enough, it swings in wide arcs, effectively dead angling unsuspecting players (see below for an explanation on dead-angling). A patch significantly nerfed its actual damage output, and its swings are fairly telegraphed. However, it's still one of the more dangerous, easy-to-use weapons out there, if just for how versatile the moveset is.
The Halberd; undisputably the most broken of the four, it combines early accessibility with damage even higher than the attack rating suggests, fast attacks if they connect, deceptively long reach as with other pole weapons, and ludicrous damage modifiers upon clashing with an attacking opponent at the same time.
The Zaphander/Chaoshander Build. Just enough Strength to use the Zweihander sword two-handed (16), upgrade it to +5 Lightning (for the aforementioned armor piercing) or +5 Chaos (for higher attack ratings), combine with Havel's Armour (highest poise) or Giant Armor (highest physical defense and second-highest poise) and a Grass Crest Shield on your back for stamina regen. You suddenly have a Mighty Glacier that can keep swinging forever, with armor that negates the disadvantages of the sword's slow swing speed. Mix in a couple of rings, you've got a Lightning Bruiser. This can be achieved before level 30. The player can then put the next 50-100 levels purely into Endurance, to boost stamina and equip load, Vitality to boost health; and a dash of Attunement to use Great Combustion. Again, pretty much universally hated for being generic, bland, stupid-easy to play and frustratingly popular. A number of its components were nerfed in v1.06, but it can still be very annoying.
The Giantdad, a popularized version of the Lightning Bruiser build above, and by far one of the most used and hated variants: it combines the bare minimum of stats to use Giant's Armor (the highest physical defence in the game), the aforementioned Chaoshander to deal very high damage, the Grass Crest Shield for a huge increase to stamina regeneration, and most importantly, the Father's Mask and rings to make the build light enough to give the player full mobility. It all comes together to create a Lightning Bruiser that's very hard to hit, can tank a surprisingly high amount of damage, stunlocks you easily, and dishes out the pain. Every. Single. Swing. note Just don't tell anyone you raised that dexterity stat.
Abyss spells, specifically Dark Bead (a fast-casting, multi-projectile spell that easily lands multiple hits up close and spreads over akin to a shotgun), Black Flame (Great Combustion dealing even greater stamina drain), and Pursuers (a Homing Soulmass variant that's significantly more persistent, and isn't stopped by the Silver Pendant, which is made to counter Abyss spells). Since you can only obtain them through Artorias of the Abyss, they can also be considered as Bribing Your Way to Victory.
The Greatshield of Artorias for defense. Even with its average elemental defense, this shield boasts the highest stability in the game, blocks nearly every status effect (save for Curse), and doesn't require as much strength or equip load to use as Havel's Greatshield. When equipped, a mook's attack can barely chip one-tenth of the player's stamina bar, and most boss-level physical attacks (minus elemental attacks and some very few particular special moves) — Artorias' triple backflips, Smough's hammering, Ornstein's spearing, you name it — which can normally break through a defense in two hits become scratches on its surface without costing much endurance. When equipped with Havel's Ring for equipment load increase and Cloranthy Ring for stamina regeneration, the player can take on literally every hit in a boss fight while slowly chipping off the boss' health bar, making the fight a battle of attrition needing little efforts and skills to win. The fandom has a good reason to believe that had Artorias been with his greatshield in his encounter with the player, we would have been toasted.
While its stability is not as high as the Greatshield of Artorias, the Silver Knight Shield comes very close. In exchange, however, it is only a medium shield, thus it has lower weight and is still able to parry. It also has a better lightning damage reduction than the Greatshield of Artorias, which will mitigate other pesky gamebreakers.
In terms of damage per second, there is nothing quite as overkill as using fast-hitting weapons like the Falchion, which has some of the fastest swings in the entire game, buffing it with a powerful miracle like Sunlight Blade, then applying Power Within on yourself. The result is a frighteningly powerful Glass Cannon that can keep spamming the attack button and even decimate bosses within the buffs' durations, if not seconds, and will usually down a full-health player in no more than four unblocked swings.
Some of the more aggravating PVP techniques are also laughably easy to perform with devastating results. To wit:
Dead-angling, where you circumvent an opponent who has their shield up with an attack which is likely to hit their unprotected sides without even trying. Of the better weapons to abuse this somewhat questionable strategy, none are more dangerous than the Great Scythe, which also causes bleed damage to keep the pressure on your unfortunate victim, the Murakumo, whose moveset is almost entirely based on this strategy, and the Black Knight Greataxe, which was already explained above.
Turtling, in which you use a spear or rapier and hide behind your own shield (heavens forbid you if you're using Artorias' Greatshield) to poke your opponent to death. This strategy got slightly nerfed in a patch which increased the stamina drain when doing thrusting attacks with your shield up, but it's still annoying to face one since you have to risk trying to break their guard while taking damage from their pokes.
Backstab fishing, where the player does nothing but circle around their opponent in order to backstab them, allowing for instant massive damage from a Critical Hit, made even worse if they use the Hornet Ring for a solid 33% (50% pre-patch) increase in critical hit damage.
All the above are not so bad compared to stacking Poise and using any weapon (usually a Game Breaker like the Claymore) that can easily stunlock low-poise opponents, a strategy otherwise known as poise race, where the fight usually degenerates into which player can break the other's poise first and stunlock them into oblivion.
Before a patch that reduced its overall usefulness, the Iron Flesh Pyromancy was known to turn boss battles into a cakewalk due to the massive increase in physical defence and poise, with the added effect of making light and medium attacks bounce off the user. And since it's a simple passive effect without any stat adjustment, you don't need a high Intelligence stat or a maxed-out pyromancy flame to enjoy it.
Because pyromancy doesn't scale with any stats other than Attunement slots, it's very common for low-level griefers to bring in a fully upgraded pyromancy flame and a powerful spell like Black Flame or Fire Tempest, allowing them to wreak havoc against equally low-level players. Most beginners have a hard time countering this sudden leap in power, let alone have the reflexes to dodge them if it's their first time.
The Great Scythe is easily the best Dexterity weapon in the entire game. It combines utterly ludicrous damage scaling with excellent reach, insane base damage, a very versatile moveset, and some of the best dead-angling capability of all the weapons. Oh, and just to round out the package, it's fully buff-able and also has a Bleed effect. Combine it with Power Within and some buffs, and nothing can stand against you.
Its boss soul equivalent, the Lifehunt Scythe (forged from the soul of Crossbreed Priscilla - You Bastard) requires more forethought to use, but is potentially even more terrifying. It has the same powerful reach and move set, and trades slightly lower stat scaling and the loss of buff capability for slightly higher base damage and the deadliest Bleed effect in the game. Most Bleed weapons inflict 30-35 points of Bleed buildup per hit and once the opponent's Bleed bar is full, they take about 30% of their max HP as damage. Priscilla's power of Lifehunt causes the Scythe to inflict 50 points of Bleed buildup per hit and once the opponent's bar is full they take 50% of their max HP as damage! The drawback is that each hit also inflicts 40 points of Bleed buildup on the wielder, with the same danger of slashing their life in half, but a Bleed-resistant set of armour and the Bloodbite Ring can give you so much Bleed resistance that this isn't likely to be a problem, and even if it is, a simple Bloodred Moss Clump can negate it again. Your opponent is certain to die of blood loss before you do.
The Gold Tracer, a dex-based long dagger that has a huge variety of attacks (which also makes it difficult to parry) and, more importantly, builds bleed damage at an astounding 40 points per hit. Thanks to its light weight, it's a great choice for a side weapon.
A rather localized example is the Golem Axe, a boss weapon that has the ability to launch a wind blast with decent damage and heavy knockback. While this is usually really nice to have but not amazing (granting heavily melee-geared characters a ranged option that scales with Strength), its greatest strength is the ability to turn the Tomb of Giants into a complete non-threat, by using said ranged knockback to throw all of the area's Demonic Spider enemies off of cliffs without them even getting to move from their spawn point... incidentally turning the entire zone into a pretty damn good soul farming spot.
For player-versus-player, a few rings stand out.
The Dark Wood Grain Ring, which changes a player's fast roll into a ninja flip which has incredible speed, invincibility frames, and mobility. Good timing with a fast roll can allow a skilled player to cheese through almost any attack; a ninja flip makes it borderline effortless.
The Ring of Favor and Protection, which gives a 20% boost to HP, endurance, and equipment load. It may not look like a significant increase, but what truly boosts it to game-breaking levels is that these effects stack with other stat-boosting equipment such as Havel's Ring and Mask of the Mother, which can make a normally Mighty Glacier build into a seemingly invincible Lightning Bruiser with a metric crapton of HP. These boosts are so practical that most players would recommend to always consider reserving a ring slot. Additionally, because it's available in a early level area, it's the go-to ring for low-level griefers.
The Hornet Ring, which boosts critical damage by 30% (50% before a patch), when combined with weapons that already multiply critical damage such as rapiers and daggers, can almost one-shot near any build with a backstab or riposte. Even without a critical hit multiplier, the boost is enough to make that already powerful Claymore or Great Scythe hit that much harder.
The Bellowing Dragoncrest Ring, which boosts all magic damage by 20%. Doesn't seem like much, but combined with a spell that can hit multiple times such as Homing Crystal Soulmass or Dark Bead, it becomes essential on most mages. Even warriors who only dabble in magic or pryromancy can abuse it — especially pyromancy, thanks to pyromancy spells requiring almost no stat requirements.
The Red Tearstone Ring, which gives the player an absolutely massive 50% attack boost with any and all forms of weaponry, spells, and critical hits, with the only catch that the player be under 20% health to activate. When it does, however, the duel quickly becomes a sudden death match, as one mistake will either kill the player who's already half dead or the player who thought they had the match already in the bag.
The Black Bow of Pharis, coupled with the Hawk Ring, gives you a sniping weapon that allows you to chip away at the game's Demonic Spiders from far outside their aggro range.
A non-combat-related example (at least not directly related to combat) is the Fog Ring, the new version of Demon's Souls own Game Breaker, the Thief's Ring. It makes you translucent and hard to see, basically drastically reducing the aggro ranges of most enemies. This makes picking them off at range even more of a cakewalk, and breaks the challenge of some levels right across your knee, as dangerous combat encounters with multiple opponents are reduced to a series of simple duels to be handled at your leisure. It's particularly useful for avoiding attracting the attention of ranged attackers when you're engaged with something else, such as the lightning-throwing snakemen in Sen's Fortress while you're trying to navigate the swinging blade traps, or the bow-equipped Undead Crystal Soldiers in the Duke's Archives.
The Balder Side Sword earned the Fan Nickname "Baller Swag Sword" for its high Dexterity scaling, longer reach than other straight swords, and moveset; particularly the strong attack combo which consists of multiple consecutive thrusts (making it a good candidate for Leo Ring wearers), as opposed to the Longsword or Sunlight Straight Sword which alternates thrusts with upward slashes, and other straight swords which lack a thrust attack altogether.
Santier's Spear. Normally, it's an overly heavy spear with underwhelming damage and average moveset, with its durability of 500 making it a good candidate for no-bonfire runs. However, once you bring its durability down to zero, instead of becoming next-to-useless in combat, it turns into a very powerful unbreakable weapon that combines the movesets of a spear, halberd, curved sword, and twinblade, making for an impossibly diverse Confusion Fu that quickly drains away an enemy's health. As of the 1.06 calibration, it's been nerfed.
The Black Knight Halberd makes a return, and this time it gains a devastating running attack that covers a lot of ground, dealing a lot of damage in the process and punishing players who are susceptible to getting blindsided by the weapon's swings (i.e. dead-angling).
Sunlight Spear. Few things will DESTROY bosses like a couple of Sunbros chucking Sunlight Spears at it. Praise the Sun indeed! If your target is immobile, or is standing in water, expect this formerly easy to dodge projectile to outright annihilate a human opponent as well. It was MASSIVELY nerfed later.
Flame Swathe, one of the earliest possible pyromancies, is able to scatter crowds with an impossibly large radius of explosion, doesn't require much to get it to full power (and it hits HARD), takes only one attunement slot, and is infinitely farmable, provided you have a lot of Bonfire Ascetics and some time to kill in Belfry Sol.
Great Resonant Soul, a Soul Spear-like hex with relatively low requirements that can potentially rival spells that need heavy investment in either Intelligence / Faith, all with a decent attunement allocation and great number of uses per copy. With a fully upgraded, dark-infused chime, this spell can wreak havoc on anyone and everyone at the cost of a measly 500 souls per casting. It's frequently defended by its proponents by how easy it is to strafe or roll to dodge, as it doesn't have any appreciable homing capability, which is certainly true... but both its cast time and projectile travel time are exactly long enough for an attentive opponent to notice and dodge. Were they doing anything else in the meantime, or something that took longer than .75 seconds, such as attacking with a greatsword, or casting a spell with a slower cast speed (which is almost all of them)? They're either dead or almost dead. It was later nerfed just as pretty much all magic.
Don't want to get close and personal in PVP? Simple. Just get two Avelyn crossbows upgraded and enter power stance mode, where you can fire 6 bolts at once. Due to how nearly useless poise is in this game and how the Hitbox Dissonance often prevents you from dodging effectively, it's easy to get clipped with a single projectile, let alone receiving several at the same time. And since it's a weapon, the attack power of every shot can be considerably heightened by static boosts like Mundane infusion, Ring of Blades+2, and the Sacred Oath miracle. It can be blocked reliably with a greatshield, but heaven help you if you don't have the stamina for it.
Before patch 1.03, the Moonlight Greatsword could be buffed by spells. Unlike the first game, the Magic Weapon sorceries add a fixed amount of magic damage and a percentage of the magic damage the weapon did otherwise (as high as 30% with Crystal Magic Weapon). The Moonlight Greatsword does entirely magic damage and a very high amount, so using Crystal Magic Weapon boosted its power to utterly ridiculous levels.
Before being nerfed (or perhaps, fixed), the Monastery Scimitar was infamous for its parrying ability. Weapons can only parry during certain frames of their animation. Normally there's some delay between the animation starting and these frames, but the Monastery Scimitar was unique in that its parry frames started immediately and lasted longer than they do even for shields meant entirely for parrying, so it would parry just about any incoming attack at the press of a button with no effort required.
Normally, the attack time on all weapons are at the very least slow enough to only guarantee two or three hits before an enemy can dodge away. The same goes for all weapon combinations that can be Power Stanced. On the other hand, there are some weapon combinations that aren't capable of being powerstanced nor were they intended to be used together, but when used one after another can hopelessly stunlock enemies into oblivion. The only real way to escape from this is to wait until the person doing it has run out of stamina and hope you're still alive by then.
The Sanctum Crossbow has a ludicrously powerful special attack, which even un-upgraded or un-infused does some incredible damage to just about anything (it deals out around 350 to Nashandra, a boss that's nominally resistant to Dark damage, and over 700 to the Giant Lord). Infused and upgraded, it's capable of damage on par with some backstabs. All the while it's got good tracking and consumes no ammo. It's almost as powerful as Great Resonant Soul pre-patch.
The Ivory Straight Sword is an absolute beast in PvE (less so in PvP). Despite its drawback of using 10 durability on each attack (less with the Bracing Knuckle Ring), the sheer damage it does to some bosses is astounding. The two-handed heavy attack can hit upwards of 700 damage without any upgrades (against the Ancient Dragon anyway), allowing you to cut a swathe through the end-game content or through NG+ and beyond.
The Ice Rapier has become prominent in PvP due to its reach (it is the longest Thrusting Sword in the game; having the same reach as some Greatsword class weapons) and the special attack's damage output. Coupled with the counter-hit damage, the weapon is quickly becoming hated by the competitive community.
Out of all of the weapons in the game, few will come close to the sheer popularity of the Red Iron Twinblade. This weapon has become many a speedrunner's go-to weapon, capable of tearing bosses and players apart in mere seconds. While fairly tame on the PvP side due to its slower attack speed (and easy parrying), it still can hold its own in moderately skilled hands (or with a buff, due to an issue with the netcoding giving buffed weapons a significant case of Hitbox Dissonance). The issue arises from just how fast it can obliterate the AI, who have no proper response to its flurry of attacks. There's a good reason it's often called the Red Iron Winblade.
Ha ha, look at the puny little Caestus with its pathetically low base damage. Even fully upgraded it doesn't even hit a hundred! Except that it has A scaling in both Strength and Dexterity. With both stats levelled to the soft cap and power-stancing two of them, there's no health bar in Drangleic that won't utterly evaporate from spamming LB like a madman. Crown of the Ivory King adds a new variant in the Bone Fist, which has even weaker base damage but even higher scaling.
The famous Uchigatana has become this, if for nothing else than how quickly it can be picked up. It's a katana with very fast and accurate strikes, which can be upgraded to get really good Dexterity scaling, uses less stamina than most katanas in the game, and since it counts as a generic weapon as well, it can also be buffed and infused. The best part about it? It can be obtained in the very first area of the game from an NPC you can fight and kill. Said NPC is also very prone to accidentally falling off a nearby cliff, netting you easy access to the weapon. In the late game, a Hollow Uchigatana becomes a powerful weapon for a DEX/LCK build, as its Bleed effects are boosted by the Luck stat and Hollow weapons get a damage boost from Luck without having to remove its ability to use weapon buffs. This makes it moderately more damaging than with a pure DEX build and grants sudden death by Blood Loss much faster than normal. Although the recent patches have changed how Bleed works, nevertheless the Uchigatana is still a viable choice for Bleed builds.
The Refined Longsword. Yes, really. On a DEX/STR build, it becomes an absolute monster in PVE capable of devouring enemies with devastating speed, given that it has 198 attack power, plus at 40/40, with an adjusted bonus of 230, for a total attack power of 428. There are Ultra Greatswords that don't become that strong. Even in PVP, it can be a weapon to be feared, given that its high attack speed makes it incredibly difficult to parry. And that's not all; as a generic weapon, Refined longswords can still be buffed with a variety of spells and resins. Furthermore, its also very light, leaving equip-load levels for other things like armour and more health. This allows you to be fashionably attired while still being able to cut foes into teeny tiny pieces with your resin-enhanced shiv.
The Dark Sword, while somewhat difficult to get, is a beast for Strength builds. Not only does it have extremely high scaling with Strength (especially with a Heavy infusion), but it also has fantastic base damage on its own. Just to make it even stronger, it can also be buffed/infused and it has very fast attack speed for a Strength-based weapon, allowing you to easily Stun Lock opponents or effectively trade hits. While it can be parried rather easily by experienced players in PVP, its terrifyingly effective in PVE and can still catch newer invaders offguard. While it was nerfed in Patch 1.09, it's still a quite effective Disc One Nuke for Strength builds until better weapons start becoming available to them.
The Astora Greatsword gains its Game Breaker chops by being the most light-weighted ultra greatsword, and its scaling with Crystal, Chaos, Lightning and Dark can reach an absurd S. Even when you infuse it with Refined, it gets a B scaling for both Strength and Dexterity, which is pretty impressive for an ultra greatsword as light as the Bastard Sword. Additionally, it also makes for an unexpectedly good Poison weapon, an infusion uncommon enough to send enemy players panicking when the poison procs. And prior to the first DLC update, its rolling attack couldn't be parried, but it is now patched and the rolling attack is now no longer something to dread.
The Lothric Knight Sword is effectively the Baller Swag Sword v2.0, having the same moveset and can be infused with Sharp to have even better DEX scaling than its predecessor. Or, you could infuse it with Refined to give it the same B/B scaling as the Longsword mentioned above. But if you're more of a spellcaster type; a Crystal/Simple infusion will give it an S scaling in Intelligence, Lightning/Blessed will give it an S scaling in Faith, and Chaos/Dark will give it a A scaling in both. Last but not least there's also its critical damage modifier of 110, meaning that in the right hands or with the right setup, this weapon can easily end most opponents with a single backstab or riposte.
The Chaos Zweihander returns as a killing machine for sorcerers; with a relatively low Strength requirement, a build with high Intelligence and Faith can still land an uppercut which can chop away half of your human opponent's health in one hit (e.g. 802 damage for 50 INT + 30 FTH + 24 STR when +1). It seems the Legend, indeed, never dies.
The humble Caestus, while a sub-par weapon, has one of the fastest parry frames around. Its so fast it can actually interrupt the combo of fast attacking weapons like straight swords or thrusting swords once the mercy recovery kicks in (after the second consecutive hit). This works... Every. Single. Time. If one also packs a Hornet Ring, this can make for an easy win against opponents who heavily depend on R1 attacks over other less predictable moves.
In addition, a Simple infusion has become a common choice for this weapon, as it allows for continuous but slow FP regeneration. While a patch has removed the ability to use weapon arts with only 1 point left in the FP bar, this just means you have to wait a few seconds in between Skill uses, and wearing the Farron Ring can reduce that waiting time significantly, since it reduces weapon art FP costs a small percentage. Being able to spam weapon arts can be a Game Breaker all on its own, given that many Skills are powerful, difficult to predict or dodge, and/or impossible to parry.
The Grave Warden Twinblades and Spiked Mace inflict Bleed naturally, and also have Skills that throws many hits in a row. With a Hollow infusion, 40 LCK (including the 5 point boost from Hollow infusions when you have over 15 Hollowing), and 40 DEX or STR, respectively, either weapon has good damage, high base Bleed, and yet still retains the ability to apply the Carthus Rouge resin. Both have been known to inflict fatal Bleed damage before the end of a combo.
The Gotthard Twinswords can become fearsome with a Heavy infusion, when combined with high Faith or Intelligence for spell buffs plus a Simple infused item on your off-hand weapon. The combination creates a fast-hitting weapon that can devour enemies in PvE and PvP without mercy, as the individual hits are incredibly punishing, and if the opponent can't escape quickly, they'll often be dead by the end of the combo. The weapon art - beginning as a Spin Slash - cannot be parried, and can be difficult to predict, so if a player relies on the Caestus or other parry tools, they can find themselves trying to parry that which cannot be parried, and end up taking a fatal hit that they would have been wiser to dodge instead.
The Barbed Straight Sword. Here's the breakdown: Imagine a weapon that can have damage approaching that of the Heavy Dark Sword (a little bit less, but still significant), but with the varied moveset and low stamina cost per swing of a longsword, significant Bleed buildup per swing, and can be buffed with the Carthus Rouge resin, greatly increasing its already considerable Bleed abilities. That is the Barbed Straight Sword: A perfect storm of Game Breakers combined into a single and utterly devastating package in the right hands.
Due to an exploitable Good Bad Bug, the Sacred Flame pyromancy can be made to be drastically stronger than it was intended to be, giving it the ability to devastate humanoid enemies in a single shot, and due to another bug, it tends to be far more accurate than it should be due to severe Hitbox Dissonance. This has since been patched though. However, Sacred Flame is still compatible with Aldrich's Ruby (HP Regen on a critical attack) and Sapphire (FP Regen also on a critical attack), so it can be effectively turned into the pyromancy version of Dark Hand, albeit with less HP regeneration.
Great Magic Shield is considerably better than it was in the previous two games, giving the caster near-total immunity from any sort of non-physical damage on their shield. It has its limits in PVP due to its short buff time (30 seconds) and the fact that it's useless against Duel Charms, but in PVE it is incredibly strong and can make even the hardest bosses trivial. Try using it onto a greatshield, and it'll provide Nigh-Invulnerability when you're fighting against opponents who rarely kick you or attack without shield piercing weapons.
It has been discovered that there are ways of creating an extremely optimized build that possesses incredible power even at somewhat low levels. The Dragonslayer's Axe (Completely different from the Greataxe) has the distinction of having a Raw infusion that possesses damage almost equal to its Faith and other infusions. At +10, it has an attack rating of 475, significantly higher than a Heavy Dark Sword, but with no need to invest points in Strength, Dexterity, or Faith to give it that power beyond the bare minimum. Plus, it can be buffed, making it a powerful melee option for miracle and magic builds. For a ranged option, the Knight's Crossbow, with Lightning Bolts, has an attack rating of over 350+, making it incredibly powerful, and possessing no stat adjustments. With 18 Strength and 14 Dexterity, you can use both. Alva's armor, when combined with a Ring Of Favor, can be equipped with both weapons and a shield like the Dragon Crest Shield or the Spirit Tree Shield, plus a Caestus for parrying, all at a mere 15 Vitality. Wearing the Ring of Steel Protection along with the Speckled Stoneplate Ring gives the incredibly light armor defensive abilities equal to many medium-to-heavy armor sets. With Vigor and Endurance at 40, you've got a build that is insanely effective, given that very few enemies have notable lightning resistance, save the Nameless King. If you want to use buffs from Faith or Intelligence (or even Hexes), you've got room to spare to load all of those stat points into, or you can just be a low level invader and terrorize other players with less optimal builds than yours.
The now-patched Tears of Denial glitch. Tears of Denial, by itself, is an expensive miracle that allows you to survive with one HP remaining from a hit that would otherwise kill you. Due to some wonky collision boxes, however, having the buff active while jumping into very specific parts of bottomless pits made it so that your Y-coordinates would never go down unless you quit the game or die, effectively granting flight, allowing you to skip every single level and boss short of Iudex Gundyr, Vordt, the Lords of Cinder, and the Final Boss. It could even be used to kill some of the bosses by going underneath their arenas and slaughtering them while their AI was disabled. In online play, it was frequently exploited to grief unfortunate invaders, and in regular play it allowed for so much Sequence Breaking that the game could be beaten in under 40 minutes.
The Ashes of Ariandel exclusive weapon Follower Sabre has gained infamy for being a Carthus Curved Sword with another model but far more worse. With a Refined infusion and 40 points in both DEX and STR, as well as a equally similar moveset it is basically the same as the aforementioned weapon in stats and damage output, but with the annoying addendum of having an extremely fast weapon art which can guard break shields. While it doesn't inflict Bleed damage, its absurdly high damage is more than enough to kill someone by landing all 3 of its weapon skill's slashes. Since Patch 1.22 however, the damage done by both the Carthus Curved Sword and its sibling the Follower Sabre has been mercifully nerfed.
The Valorheart, while it does have rather mediocre (386 at 40 in STR/DEX, and cannot be infused or buffed) damage, has three things going for it: Its quick attack speed, ability to block attacks and avoid getting staggered as result while two-handing at the beginning of each attack (which is perfect for giving R1 spammers and abusers of the katanas' running attacks the middle finger) and its shield bash ability (which allows you to guard break turtlers and also set them up for a critical hit). When used correctly, this weapon can become quite lethal to encounter.
Yhorm's Great Machete is generally viewed as one of the only pure Strength weapons that is PVP viable, due to a combination of massive reach, lots of poise frames and some of the highest hit for hit damage in the game. This thing can nearly out space a spear and still hits like a freight train, even capable of staggering those who aren't close enough to be hit. Two handing it at 66 STR cranks its damage to a horrifying 707 which makes it one of the most powerful pure physical weapons in the game. Even at high levels, a few hits from this beast is all it takes to kill most players. The sheer power of its attacks also smashes most shields in two hits and the resulting critical (or any critical really) is essentially game over for the opponent.
The Millwood Battle Axe is becoming infamous in PVP due to its weapon art, which causes the player to charge forward at a run, and then do a shout that can briefly stun an enemy. Why? Because even in Havel's armor and with the Iron Flesh pyromancy applied, players using both can still charge at full speed, allowing them to close the distance and attack, basically no selling attacks all the way.
The Painted Guardian Sword comes back with a vengeance, as its strong attack takes little stamina to execute and can chain constantly on unsuspecting enemies. It's usually applied with buffs to make the stunlock even more frustrating for the victims.
The Ringed Knight Paired Greatswords. What sets them apart from the other ultra greatswords is that a full combo from the dual-wield stance can easily kill even players at near-maximum health, and the swings have fairly good tracking, not to mention they're almost guaranteed to Stun Lock people with just a single hit. However, they are easily countered by other ultra greatswords which have "Stomp" as their Skill, since their attack animations are fairly long and leave their users unable to avoid getting launched to the sky.
Gael's Greatsword, if just for how its weapon art transforms you into an Artorias on steroids. Unpredictable leaps and combos usually spell doom for your opponents as they try to avoid getting hit from their sides.
Looking at its considerable 16.5 points of weight, slow swinging speed, high stamina cost and having split damage thanks to its innate lightning infusion, the Lothric Knight Greatsword is perhaps a weapon one may not usually think of seeing here. What puts it on this page, however, are the following; its amazing scaling and resulting high damage with a Blessed infusion, the hyper-armor frames inherent in every ultra greatsword's two-handed swing, and its long reach as well as its ability to perform thrust attacks. Equip the Leo Ring for added thrust counter damage, and you can see for yourself how much of a monster this weapon truly is, both in PVE and PVP - the accompanying HP Regen and the ability to counter other gamebreakers through the use of its Skill are just added bonuses at this point.
Gundyr's Halberd - while its Skill "Champion's Charge" could be easily parried with a little courage and timing - is often the bane of many players due to the fact that its Skill can be used again only a few seconds after a charge ends. What's more annoying, should one get hit by its spinning attack, they will be sent flying to the ground, where their rising animation is often long enough to allow its user to do another charge - leading to a vicious cycle that only ends until either the user has run out of stamina or missed, or once the victim has died or luckily managed to roll far out of the way.