(SPOILER ALERT & TIPS) (DO NOT READ) unless you want to
Just thought I would put this out there, I have been killing him over an over again to see what he drops and so far I have found he always drops the soul stone, dragon bone helmet, and 2 random items, one of them is always a random jewel and the other is usually a charm or some crappy item, but for charms he has a chance to drop +4 vitality, +4 Dex, +4 spirit?, +4 Str, and anywhere from +6-+8 melee damage, have not seen the +4 Int yet, but it took me forever to find the +4 Str, good luck!
Also, his chest spawns a random gem and random charm, but there is always his helmet that looks kind of like a samurai helmet with mask and it is lvl 19, but the helmet stats change every time so my advice is to save your game before you answer the password an keep loading untill you find a helmet with stats you like. best you can hope for is one with 2 blue random stats of your liking 2 empty charm slots an 2 random enchantments.
Also, when farming for items, just look for good base stats an more charm slots if you can, if the item has enchantments you dont like, not to worry, you can have them disenchanted and enchant them with whatever you want later, if you have the mats anyways