Dein Nomos (宙の戒典 Chou no Kaiten / Deinnomosu?, "Immortal Law Enforcer") is a notable sword in Tales of Vesperia. It is a red-purple blade with a hollow center, and it continuously radiates an aura of energy that has the ability to control aer. The sword changes color according to its owner, and the way it cuts may change as well.
Dein Nomos was originally owned by the Empire and is to be used in a ceremony when the next emperor ascends to the throne. However, Duke Pantarei stole the sword sometime prior to the events of the story. In search of Estelle at Baction, Yuri Lowell is given the sword by Duke and uses it to break the seal, where Estelle awaits. Yuri continues to use the sword until he defeats Alexei Dinoia at Zaude, with Duke reclaiming it shortly afterward. Duke is able to wield the sword in a seemingly telekinetic manner in the final battle of the story.