All critical rolls against evil foes are automatically
successful (so every threat is a critical hit). The weapon
negates the damage reduction of evil creatures and is capable of
striking evil incorporeal creatures as if it had a +1 enhancement
bonus. Also, the weapon is considered blessed, which means it has
special effects on certain creatures. Individual arrows or bolts
can be transmuted, but affected projectile weapons (such as bows)
don't confer the benefit to the projectiles they shoot.
This transmutation can't affect any weapon that already has a
magical effect related to critical hits, such as a keen weapon or
a vorpal sword.