Yep. Power draw is just for bows. Power throw covers throwing and crossbows don't work with power anything. One thing I need to say however is that crossbows don't works as well from horseback. Only the lighter kinds of crossbow (hunting and light) can be used from horseback. You'd need to get off your horse to reload after every shot if you're using a heavier crossbow. (crossbow, heavy and siege). Bows tend to work much better from horse, and certainly in later levels where they outmatch crossbows in pretty much everything, including damage.