You cam steal skill books, other items from NPCs (i tried it in the main prison camp) by getting them in a conversation with one of your characters then clck on another character with sneaking, go behind the npc, activate sneaking and proceed to loot.
You have to watch out for patrolling npcs. Also if you stay in the stealing dialogue for a long time, the npc will catch you doing it, and end up in a fight.
