It is a processed Artifact, similar to Reg's Incinerator, that generates a mysterious blade of light. Whatever it hits is permanently disintegrated; as seen with Mitty's left eye.
According to Nanachi, Sparagmos has never been put on auction and Bondrewd apparently named it himself.
Sparagmos is an ancient Dionysian ritual of tearing apart non-believers. Their flesh is then consumed by the Maenads (followers of Dionysus), leaving no trace of their existence; very much like this Artifact's 'power'.