Divine Warrior( Faiths of Eberron, p. 146)
Through divine power, you wield your deity's favored weapon to devastating effect.
ability to t u r n or rebuke undead, Proficiency in deity's favored weapon. base attack bonus +6,
Spend a turn or rebuke undead attempt as a swift action to temporarily grant your held weapon (which must be your deity's favored weapon) either the holy or unholy property. T h i s effect applies only to the next attack you make with the weapon; if you do not attack before the start of your next t u r n the effect fades. If vou normally turn undead, this feat grants your weapon the holy special ability (DMG 225). If you normally rebuke undead, this feat instead grants your weapon the unholy special ability (DMG 226). This effect overrides any alignment or similar property that the weapon has.