Perhaps I was a bit rash. Point is, I think most of these mechanics are hardcoded, and are not going to happen.
Only very simple things can be done at this point and not be completely unlikely to be implemented.
(Simple things such as editing item requirements.)
The community have asked for xbow skills for nearly 4 years. (!)
So sorry to break it to you if you weren't aware. There is nothing wrong in the basic idea. It just won't happen.. But then again, 24 was perhaps a bit extreme since you would want 1h wpf too. 21, is still hybridizable xbow since it just requires wpf, besides many xbowers probably have 18+ strength already for melee purposes.
EDIT:
Arbalest is very common on EU. Dunno whats up on NA.. I guess you just like to melee more.
FYI, the Arbalest is an extremely powerful weapon. Shoot any target of opportunity and 1 shot lots of people. It breaks the lameness scale. When you get 1shotted, there are no second chances. It's the weapon for people that Hide and Wait. It would still be with my nerf suggestion, just they would have to wait a bit closer to the battle, and they could no longer just run away too!