Even with frost arrows it will take an extremely long time as he regenerates. Arrows are just not worth it.

The meteors are the biggest problem. You have to stay mobile and hide behind the pillars. Use silver sword or frostner for the spirit damage.

Or, breed a bunch of 2* wolves. Then bonemass melee the rest if there is anything left. (Lox can't pile on as well as wolves do apparently. I did it that way and they got him down to a third before they all died.)