The Vorpal Sword is an alien superweapon.
It is a submunition drone shaped like a sword, one of a thousand such devices which form the payload of a biosphere-killing cluster bomb. The drone generates a cutting field at the front and has powerful engines at the back; between the two, it is powerful enough to penetrate 22 miles into the Earth's crust. The Vorpal Sword can be steered manually or run on autopilot.
The Vorpal Sword was for a time loaned to superheroes by an alien race of dubious intentions. By allowing humanity to wield the weapon for a time, the aliens both demonstrated the ease with which they could destroy Earth if they so chose and drew entertainment from the way its wielders would eventually lose control of it.
The Vorpal Sword was for a time the preferred superweapon of high-ranking capes for shock-and-awe strikes. However, during the capeless uprising in San Antonio, they lost control of the weapon and it cracked the continental plate, creating the San Antonio Supervolcano. It was afterwards forbidden and stashed on Object 524.
In I Never Looked in Your Eyes; I Never Heard Your Voice, Empowered and Sistah Spooky steal the Vorpal Sword for their assault on Hell. It is subsequently destroyed by the Extermination Biodrones serving as security.