Do you think anyone cares? And we know you lie and troll here! Maybe you can kill him backstap easy difficult. But try it it on master difficult you cant exactly. And noobs basicly backstaps challenged fighters. Or you have similiar bug with enemys health (had this few times) example you can kill legendary dragon few hits. Try him again master difficult after that come tell us did you lie or did you have bug! These are only options here bug or lie.
Stop getting so aggro at the guy. I had almost the exact same fight with him on normal difficulty; the only reason why he got so close to killing me is because he Fus Ro Dah'd me right off the bat before I was expecting it (because he had no dialogue, so I had to attack him to start the fight) and I almost fell off the damn mountain.
So he's better than you. Stop trying to yell at him and accusing him of this or that. It's pathetic and I was almost embarrassed just reading this post.
Anyway, I think maybe the Ebony Warrior is Bethesda's way of telling you "We know you've done everything we had to offer. So here's a challenge to see what you completionists can REALLY do." By essentially making you fight a better version of yourself.