So, got him down. Took me two deaths, but it worked. I found out the best method in the end. Padded leggings and helmet, but for speed the Fenris chest. Frostner and Black Metal shield were a given anyway.

Arrows were useless. The only real damage came from Frostner. Those meteors are bad, but you can hide temporarily behind the "Fingers". They look bad now. :D

Full padded was too slow, full Fenris to vulnerable.

Well, I got him. Thanks for all the tips anyway! :)

Edit: Best food combo was serpent stew and lox pie for HP, blood pudding for Stamina. Even though I sometimes wished I had more stamina. I used all my medium health potions I had, or I would have died even more. I think it were six or eight. Probably six.