Greatdemonslayer claws (3.5e Equipment)
From D&D Wiki
These heavy, dark-red, metallic claws cover your hand when activated. Normally its a comfortable glove, but, when activated, it becomes too heavy for you to use your second hand.
Activation: Activating greatdemonslayer claws is swift action. You have to say "awaken", then the glove begins covering your arm.
Effect: While wearing this, melee attacks against demon type creatures, or those with demonblood(subtype), deal an extra 2d6 points of damage. This is considered magic damage for the purposes of damage reduction.