Gnarled Claw

A rare melee weapon with 13 uses that starts at 1 damage and gains +1 damage and +1 use on every kill. With consistent kills it builds into a high-damage, long-lasting weapon by late run. Damage resets at the end of the adventure, so it's a within-run investment. Maximize its potential by chaining kills on weaker enemies early to push the damage up before harder fights.