Dodge the fireball then shoot him whith your bow than close in with a claymore.
Shield yourself with a spell, calm it, than reflect that flare.
Calm him with a spell than go into a hand to hand combat.
Risk it and go right into the fight and crush his skull with a mace.
Shoot him with an enchanted bow and shoot a flare back.
Use your shadow birthsign ability to sneak attack him.
Use your alchemy ability to poison a sword and hit him with it.