elemental circlets

[Estellios]

See, this is the sort of critical information SE should include in the help text for these abilities.

Um...

Converts your attacks into fire attacks and grants a bonus to attack power. Effect fades upon reuse. MP is consumed while effect is active. Cannot be used simultaneously with Fists of Earth.

Converts your attacks into earth attacks and grants a bonus to physical defense. Effect fades upon reuse. MP is consumed while effect is active. Cannot be used simultaneously with Fists of Fire.

Also @ Urthdigger the elemental potency isn't a % increase, it's pretty much a more specialized Attack Magic Potency since it comes in larger quantities in gear/materia but only applies to one element.

Like Meleena said, the potency stuff doesn't seem to work for PGL atm but hopefully it will someday, it would be a nice use of the foot slot as far as materia goes.