A number of the items obtained from Dage the Evil have Artifact Rarity. Something that requires allot of work to obtain.
Artifact's definition is: 1)An object made by a human being, typically an item of cultural or historical interest.2) Such an object as distinguished from a similar object naturally produced. 3)Something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure.
Therefor the Artifact rarity is when a item is of significance to the heritage of a culture or historically.