with my original save i didnt kill him because he was bugged and i skipped it (not a big deal...)
but after that i tried many times until he showed up - but it was with an old save game where my char was lvl 30...
and i remember him very easy.... before i started to hit him immidietly i went to the levers and pull them both and then i attacked him with 1 thousand strikes skill - and he's dead... dunno what so hard about him...