Why can't I pay people to improve / enchant it? Of course, trainers would scale - pay more gold for better gear, some wouldn't have Arcane Smithing, some wouldn't have Ebony Smithing, some wouldn't have Corprus Enchanter or whatever it is, and when asked to do x 'this trainer cannot improve this item' could go in the log if no dialogue is available.
Of course I understand if NPC's don't have perks or if it would require workarounds, just an idea.