[@Double]
So long as this relationship between your mystical benefactor and yourself results in a narrow power set with low to mid potency of power (around the level of the other CSs), I am ok with it. 

Also take into consideration, relics can occur spontaneously, or from a long lost civilization. Or as a chunk of rock from an extradimensional source. Or as a spirit attached to an object. Creation by magician is but one route. In the case of the Relic hero in the CS page, her item was a gift, given to her by a powerful spiritual entity from Arthurian legend, and doesn't really give her powers in the classical sense.