Weapon Swap Mechanic

Hard to make a skill benefits from the weapon's stat we bound it?

Artillery Ballista is a totem and it only scales damge with +skill levels and a tactician passive and maybe elemental damage? Not sure.
Not even sure if it gets increased damage from passive tree since they're bound to weapon set 2 and get lost when i swap to weapon 1?


The problem is if i assign weapon skills set 2 to be used with ballista and a 2nd crossbow with +7 projectile levels and swap back to set 1 which have high physical but no +projectile levels (for siege cascade) ballista lose the bonus.

What am i doing wrong? Whats the whole point of weapon sets if ballista only benefit from the weapon we are using and not from the one we bound it?

Strange feature