Issue #25516: Impact effects on NPC spells that cannot be dual cast
The effect PerkImpactStaggerPushFFAimed is used in quite a few hand-restricted spells for NPCs which I doubt they'll ever be able cast with both hands to trigger the Impact perk. But ignoring those, I think there's a couple of instances where it should be replaced.
The spells WispVolley and the three ranged Seeker spells DLC2Seeker01/02/03RightHandSpell use the Impact stagger effect as well, but none of the creatures using them have the Impact perk or can cast it with both hands. I'd suggest changing it to StaggerPushFFAimed for their intended stagger, which I've done in the file.