The Demon Great Sword (魔大剣, Madaiken) is the weapon transformation of Clay Sizemore.
The Demon Great Sword is an elegantly crafted and slender longsword that features a solid black blade, surrounded in its entirety by a narrow white cutting-edge. However, the most unusual portion of this weapon is its hilt, which consists of a completely smooth cylindrical handle, attached by an unconventional arrangement of two small diamonds that form its guard.
The sword possess little extraordinary abilities. The blade itself, however, is extremely sharp, able to easily penetrate the human flesh with little pressure as well as easily cut through some of Shaula Gorgon's magic scorpion tails. When swung by an strong Meister, the Demon Great Sword can generate strong wings.