Stage One: Right when the battle begins, press triangle for a reaction command to block his supersonic slash attack. You'll have to do this throughout the entire battle. (It's easy.) Let him knock you into the air. Right when you get into the air, and he reappears, do three (or is it two?) square combos and a X combo. You can also do a partial X combo and use square to knock him into the air and then do a full combo. Sometimes he'll do a series of slashes if you get near him, so just glide/dash away.
Stage Two: He'll say something like 'know your place' and start glowing. He'll now teleport around the room. Glide/Slide Dash (preferable Dash) away from him. He'll also use Heartless Angel from time to time. You'll have a window of opportunity to knock him out of it. Double Jump/Glide up to him, and smack him. If it hits, immediately use an Elixir or Hi-Potion. He'll also unleash orbs of darkness that home in on you. Use Reflega to knock them away. He'll also move towards you while he does his series of slashes, glide away this time.
State Three: Same as the second stage, but now he'll summon meteors to attack you. Glide from side to side or around the stage to dodge this. If they hit, immediately use that ability that allows you to stabilize yourself while in the air. (Forgot the name.)
He isn't so hard, once you pin down his attack pattern.
Can't help with your other question. Use an faq or guide for synth materials.
Edit: Second Chance and Once More are very helpful if you screw up, and while Berserker Rage is nice, it definitely isn't necessary. You want to conserve MP for Reflega anyway.