Probably only the weaponskill, doc and fa books.
Yup. But it's already bad enough. Or do you really enjoy having to gather so much stuff (aquire items through farming, buying, crafting, whatever) before you can actually engage in a competetive fight and might lose it in a glimpse of a second? I don't know how it is for you, but I don't want some additional thing I need to take care of before engaging combat.
Those books could give you boost to non-combat skills.
I know, I know, but somehow it feels artificial.. Now there aren't only drugs, no I "need" to craft/farm/buy books aswell if I want to compete with others who will produce/get them anyway through mass producing/buying? It's just an additional hassle, IMO this is not the way this issue should be solved.