Originally Posted by
Slashley
The oversimplified damage formula is CharacterAttack*ElementalAttack.
The part which makes Character attack far weaker is that Assault from your weapon Grid is the same thing. So once you upgrade your Grid, Elemental becomes really good when compared to Character. So ideally, upgrade your Grid and use Elemental Eidolons.
The exception to that is, if you have Elemental advantage, you can use one Elemental attack and one Character+HP Eidolon. You'll do slightly less damage, but the 20% HP can be better depending on how much you need to survive. But again, only use this when you NEED the HP AND have Elemental advantage.