The Ark Of The Covenant

The Ark Of The Covenant is a malevolent artefact taking the form of a wrestling championship within the VOWA, known for turning whoever holds it into an evil version of themselves. The belt is defended in every match the champion is in, and is transferred linearly (e.g. if the champion lost a triple threat but was not the one pinned or submitted, they would retain). It was first contested for in an unrecorded Backstage Brawl between Sans and Jak, where it was won by the former. This would lead to Sans making his televised debut as his alternate evil self later at New Beginning in Teufort I.

Trivia

 * Despite being named after a judeo-christian artefact, the AotC belt is adorned with satanic imagery and is implied to be some sort of daemonic source of cursed power. The reasoning for this is Blitzy thinking it sounded cool and half-remembering a belt with the same name from an efed sie was briefly in instead of remembering it from Christian history.
 * While the belt has turned faces (like Sans) to heeldom, it's unclear what would happen if someone who was already evil obtained the AotC.