The Vessel of Mars was a bronze artifact used thousands of years ago as a prison by the Giants for the god of war, Mars. Trapped for thirteen months, Mars evenutally escaped but left behind some of his essence, embuing the vessel with the ability to insight rage and violence in whomever possessed it.
Anyone who touched the Vessel was prone to attack the nearest person to them whether they were friend of foe. The artifact was last known to be in Venice, Italy worth $50,000.