What could possibly be the goal designing the boss this way?

Only a hand full of her first phase attacks are anything other than slow, awkward, or not an attack you can punish.

Your weapon recoils off her back except it causes recoils when you attack from the front sometimes too.

You can avoid so many combos and attacks by just walking but you can't attack her back and if that is the reason for the back recoil, that's not an excuse for the design choice it's just a lazy cop-out instead of designing a better boss.

She'll slam her sword down and you both get to do nothing but glare at each other for a moment before the sword explodes then we can continue.

A spam grab? Seriously?

And this all creates a tedious first phase that you have to slog through to get to a second phase that is just a bunch of obnoxious hyper-mobility.

I don't really speak on bosses till after I've beaten them so I can be sure I understand the boss well, but I'm not sure I even want to invest the time and energy to beat this boss and continue the game. Their is barely anything redeemable. You can brake her weapon to fast track to the second phase but her spam combos will push you into the walls of the arena messing up the camera, unless you go out of your way to set it up so that doesn't happen.

But if I have to do work to avoid being pushed into the edge of the arena and consent/help the boss actually connect their attacks with my character, that is whole nother can of worms.

The boss is tedious and annoying for easily identifiable reasons and if we're not out here trying to make the best bosses we can, bosses that are fun to engage with. What the hell are we trying to do? Isn't the explicit point of a game, for the game to be fun?

I hate leaving flat negative feed back, this game is good, write that down. But it has to be said. This boss utterly sucks as a byproduct of the deliberate design choices. Difficulty is a byproduct of good design, it shouldn't be the goal* nor is it a metric of quality.

*Rage game's are their own genre that are not bad for having difficulty as the goal.