When the dragon tries to light you on fire with his mouth, run close and opposite to where the it opens its mouth. Once the dragon has completed with its fiery salvo, run out of his claws reach and face him. The dragon will then directly shoot out the flame that you have to catch with your magical sword (press Guard). Press Attack to release the fire from the sword to cause the dragon pain. Once the dragon is vulnerable, slash it with your sword once or twice. Run out of its way when it recuperates. The process will start again about five times. During the second bout, he will fire two salvos. You can then catch the fire with your sword. During the third bout he will fire three salvos. You can then catch the fire with your sword and so on.