So, if like me you don't really play with parry and her combo in the 3rd phase is giving you trouble, here's how I finally beat her :
Phase 1 and 2, dodge and attack, I only went for a parry if I was sure about getting a crit.,not wasting any bullets. That means, going into phase 3, I still had most of my bullets. Went for a parry when she was starting her combo. At best, I got the timing right and I got a crit., at worse, I interrupted her combo, and stunned her enough to get a couple of hits in.
So, kind of mixing strategies worked for me. Pure melee dodge/attack for the first 2 phases, then heavy uses of the firearm in her phase phase to interrupt her combo.

Getting so tired of this fight. I can get her to her 3rd phase without too much issues, but once there, I get caught in her combo that one-shot me...

The things is, you need to dodge her first before attacking (if you don't play with parry), and in her 3rd phase, I'm always a fraction of second too late, and it's game over...

I haven't that much trouble with a boss since Martyr Logarius.

First playthrough of The Old Hunters and I beat her on my first attempt. AMA

maria i can cook and clean pls marry me

Time for women, therefore simping is effective.

I want maria to put her sword against my neck and dominate me

dont tell her about the doll

If you think this boss fight is easy, try ng 3 + fowards

Her younger sister Malenia is making a name for herself I hear.

She was giving me trouble until I changed to the whirligig saw. The L2 stagger is godlike in this fight.