GF's can also learn Elem-Atk-J and Elem-Def-J which allows you to Junction elemental magic to your weapon and defence.
Junctioning elemental magic to your weapon adds that element to your physical attacks; adding this can be beneficial against enemies that are weak to an element but strong against magic.
Junctioning elemental magic to defence can reduce, negate or even absorb this element when you are attacked by it.
In the defence screen, the 8 elements are represented by a number percentage which is linked to the amount of magic in stock. If a green star is shown next to an element, you will absorb the attack and it will heal you.
Some magic can add defence against multiple elements at once.