Wind Blade

This spell creates an invisible sword made of wind, which the caster can instantly extend from his hand at will and retract just as easily. He doesn't actually grasp the blade, so he can hold something else while the spell is in use. If he's already using another weapon, however, he cannot wield the wind blade simultaneously.

Though the wind blade can't be seen, it can be heard as a roaring wind. It doesn't disturb the air around it, however. It batters targets instead of cutting, dealing 4d4 points of bludgeoning damage per round. It has a speed factor of 2. The blade strikes all visible, nonflying targets as if the caster was attacking a target of AC 10. Targets that are invisible or flying retain their normal Armor Class.

The wind blade is considered a normal, medium-sized weapon. It won't affect creatures that can only be struck with magic. The blade is destroyed if the wizard begins spellcasting, but not if he simply activates a magical item. If the caster falls unconscious, the wind blade is also destroyed.