The Blackfire Blade

A Blackfire Blade is a specific weapon enhancement.
It is designed as an assassin's blade, and used almost exclusively by the Bloody Blades, an organization of devastatingly skilled assassins.
The secrets of this blade's creation are said to only exist within that cult.
However, those who say that are wrong.
Blackfire Blades can be created by anyone with the skill, so long as they have the schemata required.
And several of these schemata exist, having been stolen from the Bloody Blades in a daring raid by parties unknown.
However, the result is obvious enough.
Blackfire Blades are becoming more and more common than they have any right to be.


Blackfire
A Blackfire weapon is aligned with the foulest of evils. It makes the weapon evil aligned, and thus bypasses corresponding damage reduction.
A Blackfire weapon is irrevocably changed. The appearance of the weapon shifts to a shimmering black sheen, regardless of what it is made of. It seems to be perpetually wet, but does not reflect the light, seeming to hoard it instead. Any room with a bared Blackfire weapon seems slightly dimmer than it should (this provides no mechanical benefit or drawback).
The wielder can, as a free action, cause the Blackfire weapon to become sheathed in the Blackfire from which it gets its name.
Doing so causes the shimmering black appearance to change to a vibrant angry red, shot through with veins of darkness. The blade then deals an additional 1d4 Vile damage on each hit.
A Blackfire weapon must be a bladed weapon of some kind.
If a Blackfire weapon is ever wielded by someone who is not of Evil alignment, the wielder takes 1d4 Vile damage every round, and cannot release their grip on the weapon unless they make a DC 20 Will save (they can attempt this save once each round).
Moderate necromancy [evil]; CL 9th; Craft Magic Arms and Armour, unholy blight, symbol of pain, creator must be evil, creator must have access to Blackfire Schemata; Price +2 bonus.