Slap Hand

Very little in the game pushes this hard. Add a Titan Glove and a knockback modifier and most enemies leave the screen entirely, and anything sent far enough simply despawns. That is the real use: not killing a Corruptor or a Wraith, but deleting it from the fight.

Enemies with negative knockback resistance turn comical. A Pinky hit with this covers a distance that has to be seen.

It rolls critical hits far more often than an ordinary sword, which is easy to miss because nothing about the item announces it. Reforging for damage rather than knockback turns it into a reasonable weapon instead of a novelty, and a later patch moved it out of joke territory entirely.

The Skeleton Merchant only carries it during a Blood Moon, so you have to be underground during one and lucky enough to run into him. Keep the money on you rather than in a chest at home.