Sorry that there's no commentary in the video, but the strat is easy. Get a baseball bat (it should be new, not damaged). Level durability if you want, but it's not necessary. Then wait until she does her figure eight spin attack, meet her and spam the parry button. Just spam it. The parries will mostly work. Then avoid her other attacks and wait for your structure to recover (don't run, walk, so it will recover faster).
Also you should damage her HP at least a little too, because I think her structure will recover otherwise. Just like in Sekiro.
As for her second phase, I'm very bad at it, as you probably noticed.
![](https://i.ytimg.com/vi/vIL9pk0j9f4/maxresdefault.jpg)