So on another topic:
Remember the ousei/vigorous weapon skill? Do more damage when your remaining % HP is higher? Apparently that's not added to assault (nor element, for that matter). It's a % bonus to damage (dunno how it'd interact with other otherBuffs type stuff). The large version at lv 20 is about +15.5% damage at full HP. The small version at lv 20 is about +8.5% damage at full HP.