Needs review
Source: Quintessential Elf 2

Description: You may infuse your woven light items with negative energy.

Prerequisites: Any Weave Feat, Ability to Rebuke Undead

You can create items that have a negative energy taint. Applying this taint costs the weaver one daily use of his rebuke undead ability.

This is an uncommon taint that can be added by a weaver when using any of the Weave Item Creation Feats.

Infusing a weave with negative energy places it firmly in the realm of fundamental evil. Good aligned creatures touching or bearing the object suffer from a negative level until they discard it. Evil creatures gain a +1 profane bonus to Will saves. Weapons tainted with negative energy deal evil damage for the purposes of Damage Reduction and have a +2 profane bonus to damage when striking good creatures. Ranged weapons do not confer this bonus to their ammunition.