Banishing

Banishing: These weapons do 4d6 damage on a hit, and kill an eligible target on a confirmed vorpal hit (natural 20) if the target is below 1,000 hit points. If the target has more than 1,000 hit points, or is otherwise immune to instant kills (e.g., red-/purple- named bosses), they will take 100 damage.

This effect is typically found on piercing weapons (Shortsword, Rapier, Bow, etc.) and bludgeoning weapons (Mauls, Warhammer, Handwraps).