One thing that annoys me in Morrowind and Oblivion especially is the fact that you use material to make armor and weapons, but they all look the same. In Daggerfall, you could find three or more Steel cuirasses that looked different. One was basic, one was shinier, one had gold trim, etc.
I'd like them to add more to the sets of armor. Make the material list, then make different designs for them. So if I have a full suit of ebony armor, I can get into a duel with a warrior with a different set of ebony armor. It'd add so much more customization, I would absolutely love it. Hell, even having two sets for each material would be a giant leap forward. In Oblivion, I felt like I would always just wear Steel armor until I got a high enough level to get Ebony, then never changed it. --- I'm untouchable (you get it??)