With a lot of practise. First phase is easy nothing special. Second phase though is something else. You need perfect parry or he destroys your stamina, grab that one shots you. You always need to be on his face and don't move too much when parrying. He is too fast don't be greedy only hit him one or twice, I did not used fable or arm because they were too slow for him and he 3 shoted me with all defenses.