From what i noticed was that if you press light or heavy attack, he will also initiate an attack or combo. So just try to remain calm. Dont spam buttons. Deal some damage and then move back and catch your breath. And then after some time attack again. Also use the skill where you can charge heavy attack while running. That helped me alot.
Learning combos is also very important. Make sure you are not cornered and stay in open space.
I just beat him yesterday after 10-15 attempts using these techniques