[Autumn]

I don't think this is technically a bug since Gun upgrades used to count only for basic attacks, and so does power boosts like Further Madness/Ring of Thorns/Upgrade skills/Passives like One Shot Wonder.

You'll notice that Further Madness/Ring of Thorns/Upgrade skills don't actually add to the SWA of stuff like Shinken either, and only to basic attacks so I'd be surprised if this is somehow a bug.