the first layer (clothing) would consist of simply shirt and trousers/pants/whatever your country calls them. if Bethesda decided to go for it they could probably provide socks and stuff- but who cares?
the second layer- armour, although it may sadly be everything
pauldrons (IMPORTANT) Greaves,cuirass,gauntlets/vambraces,boots/shoes,helmet...
the 3d layer would include
skirts, ponchos,cloaks, standards (flags) random totems and collectibles,
4th layer (that is actualy between 1 and 2) would be like extra clothing and armour between the two (chainmail or leather under playe for example) it is the most realistic but i would argue its a little overboard.