The Tokyo Mew Mew girls have a habit of using these. Mew Lettuce, the worst offender, has a pair of castanets, though at least she shoots water from them. Mew Pudding has tambourines that can rend the earth and encase a target in jello, and Mew Ichigo has a pink heart-shaped bell that shoots out waves of sparkly healing power (the remaining two team members, Mew Mint and Mew Zakuro, use the more reasonable bow-and-arrow and whip, respectively).
Cure Lemonade from Yes! Pretty Cure 5 also uses castanets, which is odd, because her teammate, Cure Mint, is an expy of Mew Lettuce.
The paopei of Soul Hunter are artifacts of incredible magical power, so they come in all sizes and shapes.
Several anime have characters who use yo-yos as weapons; while this is not as implausible as it sounds (according to popular legend, yo-yos were in fact weapons originally), it nonetheless stretches things when they have explosive yo-yos, which can go off several times without being destroyed themselves... Probably the most spectacular example of this weapon is the Robot Romance classic Combattler V, a friggin' GIANT ROBOT that wields yo-yos with blades that slice enemies like a rotary saw.
Yo-yos are just the beginning. If you're a sukeban, you've got to have a "signature" weapon. Examples include bicycle chains, cup-and-ball toys, bamboo umbrellas, guitar picks (shuriken style), billiard balls, and even a bowling ball carried by one really enormous schoolgirl.
Read or Die. Some people use paper fans. And then there's Yomiko Readman, who uses just plain paper.
There are a number of characters in the various Read or Die/Dream canons who can use paper as weapons called Paper Masters. There's also a character in the Read or Die manga who wields giant matches. And later on another character wields a giant protractor.
Haruko, Naota and Atomsk from FLCL all utilize electric basses (and a guitar) to great effect. Electric guitars are apparently the weapon of choice for extraterrestrials. They're also used as baseball bats.
Panther Claw head Hiromi Tanaka from Cutey Honey The Live, in addition to having a stomach that can shoot missiles, uses frozen seafood as a weapon of choice. I swear!
Some of the Exorcists in D.Gray-Man have Innocences that are shaped like ordinary weapons, like a katana or a hammer, but most of them are very strange. We've seen characters with acupuncture needles, pendulums, soccer balls, and what looks like harp strings.
Violinist of Hameln has most of the characters fighting with musical instruments. The main character uses (guess what) a gigantic violin, his friend Raiel plays a solid-gold grand piano, and his sister Sizer wields a Sinister Scythe with a flute imbedded in the handle (though to be fair she actually makes more use of the scythe part; her flute is mostly used to summon the Valkyries). Of course, the results are pretty awesome, but still.
More amusingly, the series protagonist (Hamel) has been known to throw Flute (and his other allies) at enemies as a form of attack.
He also occasionally throws his instrument, though this rarely turns out well.
Spoofed in the beginning of this Abridged episode of 5D's, where Jack throws his card at Yusei from atop an elevated highway. Yusei not only catches it, but throws it up right back to him.
Respoofed in the Robo-Jack mini-arc where Yusei tosses Jack a card while both of them are riding their D-wheels at 60 mph.
In the original manga, Jonouchi's former gang uses yo-yos as weapons, and rather lethal ones at that.
Heck, the original manga could be counted on to demonstrate this at least once a volume for the first seven or so, with various levels of realism, as it tended to cross over with "improbable objects used in improvised games." Notable improbable weapons include a can of specialty spray paint, which Yuugi used to draw a maze on asphalt while dodging someone which he then set on fire to incapacitate his opponent.
In Yu-Gi-Oh! GX, Amon and Ekou both use explosive cards whose effect read as instructions on how to detonate it.
GaoGaiGar's "Driver" weapon series (Dividing, Gatling and Bolting) are apparently giant, space-warping hardware tools. Meanwhile, HyoRyu, EnRyu, and their combined form ChouRyuJin use the ladder and crane of their alt-modes as giant tonfas. FuuRyu and GekiRyuJin fire energy missiles from the churner of a cement mixer. Big Volfogg uses a motorcycle's exhaust pipes as a machine gun. And then there's Mic Sounders...
Speaking of HyoRyu and EnRyu, they also have the Pencil Launchers, and ChoRyuJin can use the Eraser Head. They are as silly as they sound.
And of course, The Captain Koutarou Taiga's preferred weapon is consistently a golf club. Even when he puts on his ID Suit. He even calls the attack.
TITANIUM HEAD DRIVER!!!
Get Backers. Perfume, mirror fragments, thread, needles, and cloth seem to be the worst offenders. The "poison perfume" is justified by some kind of magic, but... thread. In practice, it's pretty badass (at least in the manga), but...
In the manga they were not threads but harp wires. Slightly more believable as weapons, but still unique.
Busou Renkin has plenty of these. Exploding fun balls, and many more.
Hagi's signature weapon in Blood+ is his cello case.
A cyborg assassin in Ghost in the Shell: Stand Alone Complex uses a gun implanted in her right arm that fires coins. Just how it manages to shoot rolls of coins -assuming they're not just a solid, welded-together stack thereof - in a way that would make a SPAS-12 combat shotgun green with envy is never explained. Her reasons for using them are readily apparent, though; she appears to have distinctly anti-capitalist principles, so the coin shotgun may be her idea of irony.
Pics! Unfortunately, as far as US currency is concerned, only dimes fit right in a 12 ga. and they are too light to do much damage at range. But it works! in theory.
To be fair, it was most likely a railgun of sorts. Even the Major was confused by it.
Katekyo Hitman Reborn!. First there's Joshima Ken, who uses different sets of teeth to adopt the abilities of different animals. Kakimoto Chikusa who uses yo-yos that shoot out poisoned needles. M.M who uses a clarinet that, when played, creates special sound waves that cause the substance the clarinet is aimed at to boil instantly, which is called 'Burning Vibrato'. Levi who uses umbrellas that discharge electricity. Bianchi who specializes in poison cooking. I-Pin who enhances her martial arts skills with special gyoza dumplings laced with garlic, which numbs the brain and forces the victim's muscles to involuntarily move on their own.
Tsuna's woolly mittens. Hibari's handcuffs . Gamma's pool cues, Shamal uses mosquitoes, Kikyou killed Genkishi using freaking flowers, Lambo's electric cow horns, Vongola IV's fork. Amano really has a thing for unusual weapons. Most recent is Daemon Spade's playing cards, which are faithful to the name of their user and able to make mind raping illusions.
If you don't think a blanket woven out of the strongest metal in the world, or being able to use your blood as a weapon is improbable, then you've got no idea. Black Cat indeed features some improbable weapons.
Dr. Black Jack has been known to use scalpels as weapons.
Outlaw Star has Twilight Suzuka, who is a master of the bokken that would make Tatewaki Kuno green with envy. Not only is her bokken the weapon she dispatches her quarry with, but she is so skilled with it that she can smash massive craters in solid stone and steel from a distance with a single swipe of her sword (using this on the roof to escape in her debut episode) and cut a bus cleanly in half with a single vertical swipe.
Ranma ˝, as the anime that gave us Martial Arts and Crafts, naturally has an equally bizarre and improbable array of weapons for martial artists to use.
In the main characters alone, Kodachi (gymnastics ribbon) and Happosai (pipe), Mousse (who throws everything bar the kitchen sink), Ryoga (bandannas as projectile weapons) and Shampoo (chui with oversized heads, they're like basketballs on short staves). Ukyo (high speed cooking and batter as liquid cement, as well as a sort of spatula thing.
The oddest weapons, however, tend to be seen by the minor characters- and the anime outdoes the manga in this regard. There's Sotatsu Jikei'ien, who wields ink, paper, and a calligraphy brush the size of a man, Tamari Kaminarimon, who uses tops, hacky-sacks, thread and a kendama as weapons, and can presumably also use playing cards and marbles like her fellows do? Prince Kirin uses chopsticks and rice.
In Rhythmic Gymnastics, this is the trope to bear in mind. The rules explicitly forbid direct punches and kicks, but objects like balls, ribbons, hoops, juggling clubs (and each with some deadly upgrades in Kodachi's set) are permitted. Kodachi even threw her ribbon around an audience member, her brother Tatewaki, and threw him at her opponent and wasn't fouled by the ref.
One Piece should be a chief offender of this trope, as characters have used every imaginable improbable weapon and then some: spinning tops, water, perfume, a saxophone, baseball bats, paint, static cling, mascara, clouds, ropes, ramen, Prehensile Hair, guns and lasers powered by cola, snakes, eyelids (yes, winking can be deadly), and bamboo. And let's not even get into some of the weapons the characters make with their Devil Fruits.
No, let's, actually. Exploding mucus and breath. Wax as hard as steel. Soap that can clean the strength off of an opponent. A Living Shadow. Ghosts that hollow out the victims' spirits, sending them into depression. Strings used to sever limbs and make People Puppets. Syringes (from the character's hands) filled with hormones used to Gender Bend oneself and others and make oneself grow. Scissors that can cut anything as if it were paper. A needle used to stitch anything to anything else. Tears turned into whale-shaped projectiles. Biscuits molded into golems and armor.
Many of the O-Parts in 666 Satan qualify, especially Futomomotaro's Mackerel Sword which is even weirder than it sounds: it's a rigged mackerel with a hook for a handle that can release methane gas.
In Ashita no Nadja, Sylvie uses a parasol as a sword, and Grandma Anna loves to swing her frying pan around.
In Speed Grapher Saiga uses his photographic camera as a weapon. In truth, it's his eyes that emit strong energy flash the camera just focuses it. He doesn't realise that at the beginning though.
The Law of Ueki's sequel runs on this trope. Among the weapons found are mops, hair dryers, a suitcase full of money and a washing machine.
Part 4's antagonist Yoshikage Kira, when in disguise as Kousaku Kawajiri, uses a new found Stand ability to weaponize Kousaku's son Hayato, turning him into a bomb trigger that kills whoever tries to investigate Kira.
Weather Report has weather powers (surprise!) and he uses a rain of poisonous frogs, holes in the ozone layer and his urine in battle.
The Big Bad of Part 7, Funny Valentine, takes this as far as it can go - he fights using improbability as a weapon. No, you didn't misread that. His weapons are the concepts of improbability and luck. With Never the Selves Shall Meet as a backup plan.
Tamaki Damo from part 8 has the ability to soften people's bodies to the point of melting into a puddle. His weapon of choice (albeit, more of a torture device, than a weapon) is a folded 1000 yen bills, which he uses to cut and dismember his victims, after their bodies are soft enough. He also uses 5 yen coins with his fingerprints on them (people who touch his fingerprints start to soften).
Everyone in Hunter × Hunter. To name a few, there's bank interest, gum, a dart board, a vacuum cleaner, a giant pipe, and a fishing rod (used by the main character, no less). All of which are put to serious good use, like fighting giant ants bent on world domination.
It goes both ways: The aforementioned dartboard is a weapon of one of the ants. Other weapons that don't have their own tropes include a cell phone, fleas shot from a sniper rifle, a book (its text, not as a blunt object), needles, teleporting gorillas, a volleyball, one's own detached fingertips, a tiny floating birdcage, a surfboard, planet Jupiter, explosive mosquitoes, a slot machine staff, and an entire savannah the user can transport to the immediate area.
Rozen Maiden much? Okay, they're dolls, but still, Souseiseki charges at people armed with a pair of giant scissors, and when forced into melee Suiseiseki whacks people with a watering can.
One Quirky Miniboss Squad from Berserk uses torture tools as weapons. These include pliers used to pluck out peoples eyes, saws, some sort of grappling hook, a restraining device mounted on a long pole, and a massive wheel. Also, Ganishka's demon soldiers wield bizarre looking horn things that are used sort of like spears.
Durarara!!: Shizuo's trademake weapons are street signs and vending machines. Also, Mikado and Izaya, to a lesser extent, both get honorable mentions for harnessing the awesome power of the internet and unleashing it on their unsuspecting enemies.
Seiji. He managed to stab a PEN into Heiwajima Shizuo, who Vorona couldn't penetrate his chest more than half a centimeter with a knife. Shinra's destroyed some of his best scalpels operating on him.
In Soul Eater, Kim Diehl uses a lantern as her Weapon. The aptly named Jackie (Jacqueline Dupree) manages to combine flying broom, flamethrower, and explosive device in one improbable, manically grinning package.
Justin Law also sort-of counts as an Improbable Weapon. He is a guillotine, meaning that his Weapon form proper is fairly useless for Technicians in Shibusen's line of work. However, he gets around this by transforming parts of his body into bits of his guillotine form; blades on his forearms, for example.
And then there's the South American Death Scythe, Tezca Tlipoca, who calls himself the 'Demon Mirror'. We've no idea how he uses this to fight, however, because Medusa scarpers before he and his * monkey* Tech get a chance to attack.
69 shows that the Demon Mirror's powers involve creating reflections of people, which he uses to disrupt Justin and Medusa's fight.
In Sid's first appearance, he fought off four of the main characters using his own tombstone as a weapon.
And then there's the Arabian Death Scythe, who is...a magic lamp. Yes, like the one in Aladdin.
In A's, Shamal's Weapon of Choice is a set of rings. In their Pendelform, they can create teleport portals, so she can e.g. grab your magical organ.
Wendi from Magical Girl Lyrical Nanoha StrikerS has a surfboard as her Inherent Equipment. Granted, it's a mechanical weapon which triples as a surfboard, a cannon and a shield. But it's primarily an aerial surfboard.
Quincies possess small crosses that they wear as either bracelets, broaches or belt buckles. These crosses form the focus for their offensive ability and transform into combat weapons, often bows but they can be any weapons the quincy prefers to use.
Similarly to Quincies, Fullbringers form an emotional attachment to an object and that object becomes the basis for all their offensive power. Ginjou's weapon is a necklace, Tsukishima's weapon is a bookmark, Riruka's weapon is her dollhouse, Yukio's weapon is a handheld console, Jackie's weapon is a pair of muddy boots, Giriko's weapon is a pocket watch and Shishigawara's weapon is his lucky knuckle ring. Sado joins this group when it's revealed that, to produce his arm weapons, he's actually weaponising his skin.
Master Asia from Mobile Fighter G Gundam was known for taking down Mobile Suits with sashes (pieces of cloth) and BARE HANDS. He can also take down giant robots with a silk scarf.
Mahou Sensei Negima!'s Mana uses thrownyen pieces. Not only the nature of the weapon one wonders how she keeps so many up her sleeve? Her opponent used a super-powerful cloth as her weapon.
Asuna uses a fan in serious combat until she manages to upgrade into a sword. And not a war fan, an actual paper fan, and it's not entirely played for laughs due to some special intrinsic abilities. Also, Evangeline fighting with strings (it was still awesome though).
While not much of a combatant, Makie has shown an inhuman amount of skill with her rhythmic gymnastics ribbon, using for such things as crossing pits in Library IslandIndiana Jones style, as well as being able to pick up and throw people.
All that skill with it and she still only got 4th place in a gymnastics Competition....
During the Tournament Arc, Setsuna uses a deck brush in lieu of her sword to get around a restriction on bladed weapons.
Don't forget Chao's most powerful and greatest attack, the greatest psychological weapon created by the powers of the future...a copy of her family tree, which she claims contains the identity of Negi's future wife. The result? "Negi party obliterated! New record: 57 seconds!"
While Mahoujin Guru Guru's heroes keep to standard fantasy-fare like staves and magic swords when using weapons, an exception exists in JuJu. JuJu is a battle priestess of her church and carries with her a portable altar. In battle, she prays at it for her god to smite bad guys down, and He does. Taking it a bit further, this tends to put JuJu into a power-mad trance which can be broken only by someone shaking a magic baby rattle at her.
Eclair from Kiddy Grade often creates a whip made out of her lipstick by drawing a line of lipstick on a surface then pulling it off the surface as a whip.
Bakemonogatari's Hitagi Senjogahara pulls a box-cutter blade and a stapler on Koyomi('s mouth) in the first episode. When he later catches up to her on the stairs she pulls handfuls of sharp, miscellaneous office supplies from nowhere. In the second episode she states outright that she keeps them on her person at all times for self-defense.
Russia of Axis Powers Hetalia is known for using a water spout. And it's more awesome than it sounds.
He's not the only one: China uses his wok and cooking implements, Hungary uses her frying pan and Greece uses a metal cross.
And although we have yet to see it used as a weapon, Russia's older sister Ukraine is often shown wielding a pitchfork.
White flags are weapons as well. And pasta, don't forget the pasta. Why? Because Italy says so.
Blazer Drive no stranger to this trope. The characters use stickers for practically all their attacks. Dachi, the main character, uses a gauntlet that sends out wires which he uses in conjunction with his electrical attacks. Heck one of the characters uses a hammer comprised of a giant fork and a jelly roll!
The Death Note, being a notebook that kills people whose name is written in it, could easily be used as a weapon instead of a method of execution.
It is, in fact, a serial-murder weapon and if Light had ever been brought to trial would have been treated as such. Probably.
Mugen from Samurai Champloo wears geta that have metal plates fitted to the bottom of them, which he uses to deflect sword attacks. He is also able to use them as effective blunt weapons, or can throw them with a great amount of force.
There is also the leaders of the graffiti gang, who use a practice katana with nails sticking out of it.
Bobobo fights using his nose hair. When this fails, he uses his armpit hair. Not to mention one of the main enemies fights by getting eaten (he's made out of Jello). Also in Bobobo's arsenal are a Magical Girl that comes out his head, an ongoing love-drama between two squirrels that live in his Afro, not to mention cross-dressing just to make an opening in his enemies' defense.
Don Patch fights with leeks, and Bobopatchjiggler fights with a sword that has a stone head on the edge, making it, for all intents and purposes, blunt.
Ed has been known to hit people with his own detached prosthetic arm.
Basquash!, which could be called "Weaponized Basketballs: The Animation." Main character Dan escapes a gladiatorial pit fight by turning down swords, spears, and flails in favor of a ball and his trademark Lightning Ball shot.
Tiaras are not adequate projectile weapons. Their effectiveness in the show (and the effectiveness of all the weapons mentioned below), is an indication of how the writers themselves invoke this trope in choosing weapons for the characters.
Tuxedo Mask throwing roses in the original anime. Even if his roses seem to be magically sharp, with greater aerodynamics, range and accuracy than a well made dart, and notwithstanding their other powers (for example, they measure his alignment when he's Brain Washed And Crazy in the first season). He also uses a cane that can function as anything from a sword, to a bo, to a throwing weapon itself.
Sailor Neptune uses a Mirror, the Deep Aqua Mirror, as her weapon, though not as a physical one. Pluto uses a staff, the Garnet Rod, shaped like a key which holds her real magical weapon, the Garnet Orb, at the top. After their Super Upgrades Jupiter gets Oak Leaves and Mercury gets a lyre.
Sailor Venus is far above the others, as, between her tendency to weaponize everything and Artemis providing some strange tools, she has used a compact mirror (both as a very sharp Precision-Guided Boomerang and to fire the Crescent Beam. This is indeed a magical object), a mike (another magical object), and mosquito incense (not a magical object: the enemy was a mosquito youma with an army of mutant mosquito, and Venus happened to be carrying the incense to deal with the normal mosquitoes that had been tormenting her all day...).
More like an improbable shield, but in the BW arc, a Scraggy and a Scrafty pull up their "pants" high enough to protect themselves from an incoming Ember attack.
Megumi from Muteki Kanban Musume learned how to throw blackboard chalk with high precision, after she witnessed how her teacher managed to hit Miki with a piece. Later she switches to hot dog skewers, since they are easier to order for her bakery—and of course much deadlier.
Sebastian in Black Butler, being a butler, chooses to fight with silverware. In the second season of the anime. Claude does the same.
The shinigami are in on this too, but with gardening tools instead. While some shinigami have perfectly understandable weapons such as chainsaws, William T. Spears wields a long pruner while Ronald Knox has a LAWN MOWER. Said lawn mower is used to crush the heads of zombies on a cruise ship that is pretty much the Titanic, to boot.
Gintama. Where to start? Gin uses a wooden sword as effectively (if not more so) as everyone else uses their katana, and on occasion has had it modified to squirt soy sauce. Kagura uses her umbrella (which also doubles as a machine gun). In several episodes, Hijikata uses a giant mayonnaise cannon (in one episode taking out a helicopter). Bansai carries a shamisen and uses the strings to tie up opponents. The second half of episode 99 also has several characters wielding people as weapons.
In Jackals, Albert "The Giant" Gacho gets a little more extreme when he faces off against Nichol by tearing a lamp post right out of the ground and using it as a weapon. Gacho's friend Hans favors exploding fake roses, if you can believe it. There's also Turis, who has a strange mechanical spider on a "web" line, almost functioning like a rope dart but with several unique properties.
Sora of Change 123 fights with a sharpened set of house keys on an extremely long key chain.
magico is a manga that features a mage that use a broomstick. You know what he once did with this broomstick? He destroyed an island-sized castle .
In Beyblade, characters use tops to battle the tops of other characters. They have real world effects due to Serious Business.
John Doe wields what can best be described as a mix of a guillotine and a saw.
Sanae uses her very long pigtails, which end in improvised bolas, as her weapons (although not very effectively).
Touka uses a ladle, which she can use both as a melee weapon and a projectile.
Multiple characters in Anpanman. Some examples include the Donburiman Trio (Tendonman uses chopsticks, Kamameshidon uses rice paddes, and all three can throw their lids), Tekkanomaki-chan and Komaki-chan (both use bamboo sushi mats rolled up like a bo staff), Yakisobapanman (double metal spatulas), Chawanmushimaro (launches out ginko nuts and whacks them with his fan), Daikon Yakusha (daikon radish rapidly fired using a hand grater), and Datemakiman and Sakuramochi-nesan (both use bangasas as striking weapons, Sakuramochi-nesan also uses mochi as a trap for enemies).
Mahiro Yasaka from Haiyore! Nyarko-san uses forks; his mother Yoriko, a part-time monster-slayer, uses them better. Regardless, both of them are good enough that they've actually put the fear of...well, man into the hearts of the three Cthulhu Mythos deities who live in their house.
Miyu from Vampire Princess Miyu use a hair ribbon as weapon. And it is far more lethal than you could ever imagine.
Kill la Kill has the obvious Ryuko, who uses half of a giant pair of scissors like a cutlass. The Student Club Presidents all use weapons relating to their profession, which often leads to this; Omoiko's giant tennis racket, for example.
Tsubasa -RESERVoir CHRoNiCLE-'s has Fai, resident extremely powerful mage, who has a habit of avoiding a fight. But when he has to he is not above using darts to fell half a dozen Oni. And yes, we mean the darts from the game with the dartboard. You know, the ones with tips about an inch long and made out of plastic most of the time? Yeah those. Might be justified though since he and the gang are in a virtual world at that point. A video game, basically.
In Detective Conan, there are some cases with odd murder instruments, such as a fishing rod (with a rock), a bookcase (with a knife between it), the classic chandeliers (one of them had even a hidden sword), a thumb nail, and the iconic fishing line (which is not that improbable and is often not the murder instrument).
Yukiteru "Yukki" Amano from Future Diary and his darts. He manages to throw one to pierce a smartphone, attempts to do the same by stabbing another smartphone with a darts, but he pierce an eye instead, and later he throws a darts to pierce a scriptroll. Later, he uses normal weapons like guns.
In Assassination Classroom this is generally averted since the characters use regular weapons (made of a especial material but still). Ocasionally, though they use things like hena tattoos, pudding or baseballs.
Dororo's mother can battle berserk security robots with frying pans.
In the episode that introduces Giroro, Natsumi busts right through a massive array of tripwires, plastique, and claymore mines with just a leek. The finishing blow is delivered with a bookbag to Giroro's head.
Himeko of Sket Dance uses a field hockey stick in combat.