Magical Strike (3.5e Feat)

3e Summary::

Prerequisite: Psychomagic

Benefit: Any blow you strike in unarmed combat, or with a melee weapon, is considered to have been delivered by a magic weapon for purposes of penetrating damage reduction. If the weapon is already magical, it picks up your alignment instead (allowing a good-aligned character to use an unaligned weapon to full effect against creatures vulnerable to "good" weapons, for instance).