Quote Originally Posted by aswq View Post
I don't think Kamihimes have specialized weapons, it doesn't show up in their status page, that only applies to Souls.
You only need to care for specialized weapons cause they are the only ones you can use as main for Souls (Guns for Billy for example), for subs what matters most is the element, the base atk&hp and skill level.
According to the JP wiki, sub weapons gain the 1.2x bonus too, so for Billy, best results would be using all guns, assuming all your variety of weapons are within similar stats then the other factors.

Unless google translate is failing me.