Vilgax's Sword is a weapon used by Vilgax.
Vilgax's Sword is a sword that can project energy beams and coat its blade in flames, or crystals able to refract energy blasts such as Chromastone's.
Even without the flames or crystal, this sword is incredibly sharp, able to easily cut though stone, Chromastone's body, and even an entire space ship with a single stroke.
Vilgax's Sword, along with his other weapons, returns in The Ultimate Enemy: Part 2, when he returns to his normal form. How his armor and weapons returned at that moment is unknown.