Sturmford will sell that skill but it isn't always in stock. it takes at least a month for shops to respawn. if you haven't been to all the towns, save the game before entering the town. items in shops are mostly random. not sure if items are created when entering the town or when first talking to the shop keeper.as to expert disarm train, go to Thjorgard. she usually hangs out near the bank. she also will teach the master level of that skill.
sometimes those that move will go off their rail and wander who knows where.
