Actually managed to space out her grab, so a dodge backwards works. Everything else is deflect fodder.

whoever created this boss should get poisoned

This one is a pansy that needs poison and her lackeys to pressure you, the other Snake Eyes wakes up from nappy time and 1v1s right off the bat.

there's a pretty big window right after her long range shot and after successfully dodging her grab, you must immediately zone in and spam the **** out of the sabimaru

Died the most to her compared to even main bosses in my later playthroughs

Is the encounter changed in NG+ or is it changed depending on when you fight her? I entered before Genichiro and the cannoneer on top of the cliff is gone, the other two of the cannon women are replaced with a shotgun and rifle, and there's two more rifles on the second island. Not sure what triggered the change

It's always morally correct to cheese her.

Why is she immune to poison, that makes no sense from a lore perspective.

Lure her into the poison water using spring flame vent and run/jump to a safe place behind the buddha statue at the sculptors idol, so she follows you
After a few seconds, poison effect kicks into her

Keep her in the poison untill she is ready to get a deathblow

Repeat

The spiral spear is very effective due to its penatration qualities. If you charge her with it she'll try and swing at you and just get skewered. Very low spirit cost means you can easily deplete an entire health bar without even coming close to running out. Combine that with the stealth blow and this fight is much less frustrating.