Skincarver (3.5e Equipment)
From D&D Wiki
Skincarver is a magical +1 Dagger that is effective against most organic foe. Once the command word is spoken, the dagger's edges turn a bright bright red. It does an extra +4 damage on a successful damage roll. Constructs, Oozes, and Abberations are not affected by this ability.
This ability can be used 3/day and lasts for 10 rounds.