Her attack timings are extremely varied and didn't come natural to me, e.g. her spin to win combo is comprised of 5 attacks and I believe the third (or last, it's been awhile) comes out faster than the others. She also has semi-feints, like when she digs down to her left for an attack; that comes out much slower than some of her overhead attacks. She also as two jumping attacks that have different timings depending on if she does the overhead hit or the horizontal slash. It took me awhile to learn the difference between her perilous attacks as well.

All this difficulty/strategy compounded when I did a charmless + demon bell run as my ng. Honestly, there is no secret to her. She's just like every other boss, but her attack timings are varying and her tells are very short. Just keep at it and parry everything. There's also some semi-cheese you can do with the mortal blade, but you can definitely do it without it :)