I am was improving my Nightingale armor last night and noticed that the best I could do was upgrade it to 'Flawless' as opposed to something higher. I have a natural 100 smithing skill and was wearing a ring that adds 22% to smithing. I have every perk in the smithing skill tree. Any ideas why I can't go beyond flawless? When I upgraded my Daedric weapons, I got them to 'Legendary' status. I suspect it's because the Nightingale armor is magical, but I don't know. The wiki din't help.
Thank you,
Kevin