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% completion markers. That way you get more of an epic feeling when you find a sweet new set of base armor because you know that it's going to be the start of something you may use for the next decent chunk of the game.
So overall, I would rather have my armor come along with an interesting background or lore and deep customization than be something that I might be able to find in a history book. (Not that that's a bad thing, mind you.)