Unlock Unlearned Magic: Before using this code 'Save' your game as it may cause it to freeze or act erratically. During a battle go to the 'Magic' menu and continuously tap 'Up'. After a while your pointer will enter an area of the screen that allows magic that has not yet been learned to be selected.
Unlock Multi-Player Mode: When you have got a Channel Ring equip it on the character below Stahn and then on controller two press 'Select' to use that controller. Do the same with other characters on other controllers and a multi-tap to control up to four characters manually in the game.