I'd honestly just drop this bit. Say that your extensive training in acrobatic armed arts allows you to dodge any attack with Weapons. Unless you're a Jedi there's really no sensible reason that you could avoid bullets while holding a weapon but not while unarmed.
I thought about that too.
The reason for tying it to the clause of carrying/wielding the weapon is that the rules ask for it (at least in my opinion). If you transfer a trapping it has to tie into the skill it is transfered to somehow. Seen from a realistic standpoint dodging ranged attacks with weapons is questionable at best. In order to make the transfer work you have to adapt it to the new skill-set (as in the before mentioned example YW147 where something similar is done to the guns skill).
Basically the reason is my understanding of the rules on the transfer of trappings. Simply taking one unaltered trapping and put it with an other skill is not in the spirit of the rules in my opinion. Yet I have allowed it when I'm GMing because it isn't a huge deal.