Tough battle, but once you get the hang of the pattern, you'll be alright. Hold the left trigger and pound on A to reflect his magic back at him while doing a clockwise circle around the screen to avoid any other fireballs coming your way. Any time he gets in close enough for Saphira to breathe fire, make sure you use it, as this does the most damage. Just keep repeating that until he's down. If you get low on health a dove will spawn, but chances are if you get that low you'll die anyway.