Seriously. He is BY FAR the most powerful enemy in the game. I just played trough the quest on my orc 2 hand heavy armor character at level 12 and he kept one hit killing me. I used Berserker rage AND a resist frost- potion and he still one shotted me with the frost spell. If I didn't happen to be a werewolf I would not have been able to beat him. He is just some random dude, yet he is MUCH more powerful than Alduin, Harkon, and the whole Stormcloak rebellion combined. Why?!

Hate to be 'that guy', but I didn't have any trouble with him. I just kept hitting him with lighting bolts until he went down. He never even got off a shot at me.