Hahaha! I just went through that frustrating fight yesterday. Got blown around all over. The most frustrating part is losing my weapon repeatedly, then having to find it and reequip it. It helps to have a leveled companion (Wabbajacked Lydia, in my case) and a conjured flame atronach. Together, we kicked his buttocks. Lydia lost her ebony sword permanently, though. Could not find it anywhere afterwards. That took a while to get over. Ebony weapons are rare at Level 30, and I'm going up the light-armor branch of the smithing tree with my high elf.

Do undead specific scrolls/spells work on the ghosts at the end of that quest? If you're below level 35 or so (assuming here that they scale to you), let your hopefully properly scaled follower distract them while you drop a Scroll of Guardian Circle on their keisters. That works on undead up to 35 and, yes, it works on bosses too. That's how I took down Red Eagle. Either stay inside the circle to heal or just chase them down to get a few good hits in while they're in flee mode. It'll keep the Shouting to a minimum too.

Scroll of Bane of the Undead will work on undead up to level 37 (UESPwiki says 30, but I've got one in my character's inventory that says 37) and can be used alongside or instead of Guardian Circle. It won't heal you, but it will send undead into flee mode as well as set them on fire.

Mind you if you're a much higher level, or the scrolls don't work on ghosts (I know they work on draugr and skeletons; never tried them on ghosts though), you're hosed. But those would be the first two things I'd try.

I took cover at the front of the room (near sarchophagus) and let my thralls and atronachs take care of them. The bandit mage more than earned her "freedom".