I'm also pretty sure that you don't get a valour bonus to any knight units with the master horse breeder, at least in my Sweden-campaing I don't. Correct me if I'm wrong but IIRC units only get a valour bonus from the master level -building if they can be recruited from a lower level building, for expample you don't get a valour bonus to bulgarian brigands because they are only available from the master bowyer, you only gain the regional bonus.