its the psychal and gun resist. if a monster have 100% gun resist (like, no dmg, immunity etc.) he ll now have 20% resist, that means u ll deal a good dmg, instead of 0 dmg.
lets say a boss in the last HP bar have 80% resist to all dmg. he ll now get the normal dmg.
and if u use a melee attack, the dmg ll be higher at spicy cuz its resist to psychal ll be lowered, but the attr bonus that is not water ll continue the same.
IE: if u deal +1k dmg with ur AP cuz u have a good soil attr, u ll still deal +1k dmg after use the shield breaker, but ur base AP dmg ll be higher.