There are quite a lot of interesting ideas summed up so far.
My favorite so far is the idea of having armor be upgradable. Using tiers for armor bases(leather tier - leather, new material leather, new material leather, etc) and then having customizations within those tiers that tie in with the crafting disciplines seems like a complicated enough system that it would make for some long lasting\interesting armors. I also like the idea of having to change base armor sets only a few in the game. Over the course of the story, I think you should likely have to change armors at like 20% completio