Exactly the same here, each fight with him seems different, when he jumps it's easier as you just roll forward dodging his landing and hit him from behind but sometimes he does not do that at all instead smashing his arms all over the place and pretty much impossible to not get hit.
You should try farming(or buying) Molotov cocktails. Get him down to half health conventionally then start lobbing molotovs at him. If you have 10 you should be able to take the remainder of his health off.