Float has a message, D. Kind of saw that coming, it might have a real message in FF4, I only tested FF2us.
In theory, there shouldn't be a message for "inflicting float" if you think about it. At least they were thoughtful... if you were
able to make a quake-based healing attack or something, inflicting float would be evil.

Elemental attacks and Weak+ don't seem to do any additional damage, Weak+ is probably unused by the attack damage routine.
The only method I can think of testing is this... give Cecil a Flame or Ice Shield (although, the armor version is better because you
don't want Cecil to evade) and give the enemy the extra element that it is weak to (Fire for the Flame Shield, Ice for the Ice Shield). That should provide an increase of damage... in theory anyways. I don't really expect Weak+ to do anything here, but I would hope it would increase the damage output by the enemy to the target's exposed weakness.
Giving the enemy an element by itself is useless since that doesn't really change the attack power unless there's a weakness to expose..
If that's how you tested, then meh.
You know what would be worthy of testing though... give the Drain element to the enemy.. and test that against the Cursed Ring with any elemental protection. See if that Drain vs Absorb behavior applies the other way around...