Weapon-specific-ness of pirate skills?

i have a random 44 atk level 15 1h axe, also made a 42 atk one at the same time. So im set. Also, is it possible, since most say even though gunslingers can use somersault kick, it does horrible damage later on, is it possible that the formula is heavily dependent on STR and not truly reflective of ATK range? Because a Gunslinger's range wouldnt be that much lower, but its calculated using their dex.