Rift Forceblade (3.5e Equipment)
From D&D Wiki
The Rift Forceblade is a weapon of pure force, a ripple in the fabric of reality that hardens the air around it. Thus, if the air contains poison, the weapon will be poisonous. If there is enough arcane energy in the air, that is included in the blade. The blade can be frozen to one patch of air by using the spell permenancy.