effect = {{p_physical_attack;{all};15;per}}
So I dunno. Always, my first suggestion will be: Try it on a different chronicle, and if it works differently report it.
*EDIT* Actually, just tested ALL B/A/S Weapons and it works fine. They all have a Buffed/Unbuffed Patk ratio of 1.15/1 , which means 15% boost. I have removed all skills from me, so I suppose that it doesn’t take into consideration things such as Bow Mastery etc.
In other words, it works the C4 way.