Are they used for the secret room near Labyrinthian? If you don't know what I'm talking about: outside of Labyrinthian, there's a covered hut that has crumbling statues and the remains of a mercenary/bandit, with a wooden mask.If you equip the wooden mask, you get teleported to a sealed room that has the statues in prime condition, and each one corresponds to a dragon priest. Trying to activate the statues just brought up the message that I don't have the required item. I strongly suspect that you'd need the dragon priest masks to activate those statues (I didn't have any of them at the time, as I sold the ones I did have off since I didn't want them; didn't think I'd need them, and I don't think I can get them back

).