Voidmetal (3.5e Equipment)
From D&D Wiki
Voidmetal is an ore found in the Voidstone Fields of the Negative Energy Plane. It is impossible to mine normally, but when two voidstones collide, the result is Voidmetal. Voidmetal is a wicked-sharp metal, capable of severing limbs, breaking shields and armor, and even cutting through heavy doors and walls like a hot knife through butter.
Voidmetal is a prized material among undead, as it can deliver the maximum killing power they so relish, and it's relatively easy for them to obtain.
When attacking an object, a Voidmetal Weapon ignores hardness, dealing clean cuts through any material other than Voidmetal or its Positive counterpart, Brightsteel. In addition, Voidmetal deals damage to its targets armor equal to the damage the target itself endured on a successful hit. If the target has a shield, the hit instead deals the normal indicated damage to the target, and half the damage dealt to the armor, and half the damage dealt to the shield. A DC 10 reflex save negates this damage.
If Voidmetal ever strikes a Brightsteel weapon, or Brightsteel armor, both weapons release a minor burst of energy that deal one point of damage to the wielder of the Voidmetal and his target.
Voidmetal has five hit points per inch of thickness and hardness 9