Crossbow and Bow seem to work differntly at long and short range, hence the point blank skill. I think they don't do damage at short range except for point blank and the arrow type damage, so no crushing or peircing. I have noticed that at long range with a fire arrow I get something like Fire 12...Crushing 50...Peircing 12 when I use a crossbow. This would be Arrow Damage, Crossbow Damage, Peircing Bonus, so I think it works.