Here are some thoughts that are not overpowered and might be reconsidered upon comming changes.

BLM 80+

"Blood gate(s)"
Allows your next spell to use Hitpoints instead of Magic Points"
Duration : 1 Min or until a spell is cast
Recast: 10 min

"Collect Arcane Strength"
Infuses your next elemetal spell with arcane power ( MAB +10)
Duration: 1min or until a spell is cast
Recast: 10 min