Tales of Tolgard
Sword spirits, also called ragewinds, are the embodied wrath of dead warriors who perished in useless battles. They are usually found in the most volatile and violent of the Outer Planes, but a few sometimes escape to the Material Plane. On rare occasions sword spirits actually form on the Material Plane at the sites of massive battles with heavy casualties.
They normally appear as a churning whirlwind with dozens of suspended weapons dancing and clashing. Their true form seems a vaguely humanoid, semisolid cloud of white or gray fog. They have no treasure beyond the weapons they carry.
These undead attack with whatever weapons are held aloft within their swirls. Each weapon acts as if it was wielded by a different individual. They delight in disarming their opponents and using their own weapons against them. If over matched, a ragewind will use its invisibility to escape.