Bone Glove

It is passive. Use any weapon and a bone flies out on its own, limited to roughly one a second, so the free damage does not scale with anything except how often you attack. Slow heavy weapons get the most out of it, because the bone comes out at the same rate no matter what you are swinging.

The bone bounces off walls a few times or punches through a couple of enemies before it dies, and it ignores a chunk of enemy armor. That armor penetration is why it keeps mattering against tough early skeletons long after its raw damage looks small.

The dungeon. Narrow corridors mean every bone ricochets back into something instead of sailing off into open air, and it is doing that while you fight normally. In an open arena most of the bounces are wasted.