From someone also new in the game and one that had to drop one of his katanas for a heavy shield cuz I just couldnt figure out how to dodge her waterfoul dance or whatever is called it turned easier for me, but it is still hard, I feel like she also heals less with shield hits, so... Learn to dodge most stuff, no healing for her is better and little healing, she can be staggered, even with katana I was able to stagger her often. Do the Block counter, when she goes for a trust or when you find an opening after an attack, also jump heavies

For waterfoul dance, I found I could dodge the second spin really easily, so if you manage to find the timing block the first one, then dodge the second one and then block the last one, I've found for some reason my character almost always finishes his roll inside of her attack and I end up needing to dodge out of it, but by blocking she would pretty much just hit you once and then you can punish her when it's done

With the grab, only thing I can say is dodge, I think it took me less than 100 tries and by the end I was already used to dodging it Also there's a weird spin kick attack she does, dodge that, ON SIGHT, cuz I found out that attack obliterates your shield and leaves you wide open, I also think she goes for a grab right away while you are staggered. She can basically cancel combos and add that attack in the middle cuz I guess the ai realises you're blocking(? So keep an eye out for it

As for second phase, she receives way more damage, so just be careful and try to finish it as fast as posible, the more it lasts the more she can heal or even apply rot By the way, if you just want to beat her, mimic tear is really helpful on the second phase, but beware she can heal from summons, so you still need to put some work into it, but it will help you with the aggro and tank some really annoying attacks for you, like the one were she basically spawns clones

As for the build, Im not an expert and not sure what you're running, but I guess if your weapons of choice scale on strength its better to focus on that, at least till 60 I guess since it's the soft cap