I beat her with the Brass Shield and the Nightrider Glaive. I didn't block things I could have easily dodged, but I kept my shield up the whole time to protect me from a bunch of her quick cheap hits. The Glaive is slow and I still got lots of hits in.

I put Vow of the Indomitable on my shield to give me full invincibility during her Water Fowl attack. I'm astonished more people haven't pointed it out. It turns her fight into a cakewalk.

Edit: accidentally called the Brass Shield a greatshield.