Equip one of the swords listed above. Next change the (Select button) to cast Light Magic. Rapidly press the select button until your magic starts to rapidly drain. Each time press select it's counted as a successfull cast and your light magic will rise rapidly. It's best to do this at a Gold fountion so you can restore mana quickly.
My light magic is 500+ without any enhancements at this level you can take out the final boss with one well targeted spell.