If a balance is needed for xbows, I don't think the right way to do so is to make the regular Crossbow 2 slots. That would kill the classic build of sword, shield, xbow, bolts. Some sort of WPF requirement would be more reasonable, but I'm still against it. Anyone should be able to just pick up an xbow, there is no skill requirement like PD or PT for it, never has been. Being accurate with it should be a different story.
