How is attack from potential on a weapon applied for a DB

Like, is it applied as overall weapon attack, or is applied to the dagger/blade that has the weapon attack. Said another way, does the weapon attack get applied to both weapon's ranges or just the weapon that has the potential attack.

For example, I have a blade that has +8 weapon attack as its potential stat. Does this add both 8 weapon attack to my dagger's range and blade's range? Or does it only add to my blade's range?

Sorry that I don't have an answer, but am rather piggybacking off this to ask a similar question: as Dual Blades use two separate "weapons" that are still in the same class of weapons, how to +% damage stats work? For example, would +30% bossing on both the dagger and blade stack to give you +60%?