These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Game Breaker: Possessed weapons when combined with a focusing on increasing Death's critical hit rate. Put the two together, preferably with a fast hitting weapon, and make sure it's something with a high attack rate, you'll be able to easily fight through the game with it and regain any health and Wrath and you lose. Use the Unstoppable ability enough points into and it can give Death back all the Wrath used to cast it, get the Abyssal Armor, you can have a 100% critical hit rate.
Getting Health Steal and Wrath Steal on Possessed Weapons raised produces insane results where the you'll gain a percentage of the damage you do back as health and wrath, up to 30%. This is broken beyond belief. Death with a build focusing on critical hit rates and physical damage can easily regain his health faster than enemies can cut it down and gain Wrath back as quickly as he spends it. Or focus on Arcane Critical Hits chance and Arcane Critical Damage for similar results with Wrath skills, which means Death can just stand back while enemies are typically too busy to bother him and only occasionally attack them to quickly restore his Health and Wrath, which even with a build focusing Wrath damage will still easily restore both with a quick melee attack.
Goddamned Bats: The Construct Adjuncts. They try to stay away from Death, then toss (sometimes exploding) rocks at him from a distance, preferably while you're in the middle of a combat with melee enemies and not paying attention to them. If you try to break through and engage them, they have a weak but fast melee attack, which they barely telegraph, to leave you staggered for the rest of enemies to catch up and gang up on you.
The Swarm. They always come en masse, sprinting at you at ridiculse speeds in order to surround you, and do a surprising amount of damage if you let them get to close. Now granted this is lessened by the pressnce of the discarded Angel weapons you find just about every where on earth that allow you to plow through thier ranks like a buzz saw through grass, but the fact that they often come parried with a Suffering, an enemy that, if you alow it, will smear you across the floor once close enough, puts them firmly in this trope. And dont get me started on what happens if you try to take them on ''without'' the angel weapons.
Harsher in Hindsight: "What Begins With War, Ends With Death" comes off a lot harsher with the fact that this game may end up being the last thanks to the collapse of THQ and Vigil.
Hell Is That Noise: The dissonant, howling scream that signifies you're about to get bum-rushed by The Swarm. By the end of the Earth level, you will learn to hate it.
Polished Port: The Wii U version has the DLC packed on the disc, and also apparently allows you to use anything in your inventory (like switch to unequipped weapons) on the fly.
That One Level: The Earth level. The game effectively changes to a third-person shooter where you have to fight the Swarm and the Suffering, everything is grey (as opposed to the more interesting designs of everywhere else in the game), and if you don't like using the guns, tough: the Swarm are too many to feasibly use melee against. Also, due to the game mechanic that shooting things with a gun (such as Redemption or a demonic weapon) = getting Wrath, you'll end up with all the Wrath you could possibly want, which is useless in that level, and virtually no health.
Demon Lord Beliel DLC because of the amount of glitches that weren't removed since it was rushed out.