So I was chatting it up in the modding board for Skyrim as to what would be the best way to implement some sort of in-game method by which to change your character's appearance. Many, including myself, propositioned some sort of magic mirror that would change the appearance of the one using it. While I am technically unskilled, I have set myself momentarily to the task of mashing together something to explain it as far as lore is concerned. My primary issue at the moment is in deciding if I should make it of daedric origin or not, and if so which daedric prince it would fall under. So, I'm seeking opinion.

Currently I'm leaning toward Nocturnal.

You could just make an illusion spell.

Or some ancient mirror of illusion, which is found in some kind of ruin.

If it were to be illusion, it would have to be purely a sensory change. Physical changes go outside of the domain. I thought it could make an interesting basis for an artifact. Seems like the type of thing, as either an artifact of illusory or physical change, which could lead to a fun story.

Still not sure which would be the best way to go.

An example of how a story could go (grimdark flavored): The mirror falling into the possession of a lord's house, the lord giving the mirror to his daughter as a gift, the daughter learning of the abilities and using them. She expires the last charge of the mirror, is found by the guards and taken as someone involved in the abduction of the now-missing daughter of the lord, and is executed. The lord tears his entire kingdom apart looking for his missing daughter, only to eventually learn the truth of the mirror by some means and then going mad with guilt. Possibly killing himself.

Instead of killing himself, have your hypothetical Lord change his visage into that of a diseased beggar. He then wanders the earth/Nirn, a loathsome miserable creature until his last breath.

Anyway, overall, I'd say that your mirror probably falls under either Mephala's or Molag Bal's hat.