Durza has three types of attacks: fireballs, flame breath, and dark magic. The worst of the three is the dark magic, so here's what you do:
1) Circle the outside of the screen counter-clockwise. Always. Don't stop moving.
2) Hold LT the entire fight.
3) Press A as fast as possible the entire fight.
4) When not blocking dark magic, press RT for a second and let it go. This will fire off 1x magic arrow.
Here's the deal: circling the screen avoids all the fireballs and flame breath; and mashing LT + A reflects all of the dark magic. You could potentially win without taking any damage at all. You'll know you are reflecting dark magic when you see your little clear, fire-magic-symbol appear in the sky (usually over little purple sparkles: dark magic). When NOT reflecting magic, shoot off an arrow, and then try to reflect again to see if he's using it... if not, fire another arrow. Repeat.
I got into a rhythm of firing an arrow(LT + RT + A 1x), mashing LT + A 3x, repeat. Beat it first try. 1k/1k, never to play the game again.