Yeah she is kind

I think she just knocked her unconscious

Not sure as the last panel show new puddles of the blood

She taught her how to kill herself. The princess is dead.

Well, but if she wanted to live that should have been her decision. I don't think killing is mercy when the person wants to live no matter what.
But.... it makes sense for the story and for that time that was sadly just how things were (￣∇￣")

Unfortunately they wouldn't give her that option. As a royal, her or her children could claim the throne eventually. So her choices were either kill herself and avoid suffering or being arrested (maybe even raped in jail), eventually killed and to have her head hang at the gates along her father's to notify the people that their royal family is gone. This is war, so allowing one to avoid suffering is mercy.

But they could have taken her under their wings, that would have been the best option I guess. If I remember correctly Alexander the Great let the family of some defeated opponents live and made them to important allies. So that could have actually worked ╮(￣▽￣)╭ Giving her a titel, some small land, a semi-important job and she could have been pretty useful (and protected by the grace of the new king no one would have touched her).

If she was in her right state of mind, I'd agree that it was her decision but asking a panicking person "hey do you want to get raped and then die or die now?" isn't going to get a proper response. Personally, I think it's mercy especially compared to rape and I insist on rape because it seems casual here seeing as the knight herself was going to get raped if the emperor didn't interfere so for the princess it's not a matter of "if" it's just a matter of which order is she going to get: raped, killed, tortured. She probably pitied the princess as a fellow woman and she ended her right there and then.

If someone is on their death bed then yes I agree it's their decision IF they have the mental capacity to do it and aren't in a coma but this is war and a panicking woman who had no care in the world a couple of hours ago and is now facing death isn't going to give a straight answer so, in my opinion, she is like the vegetable patent in a coma and should be dealt with as mercifully as possible

yea I got that impression to, I feel like the end of the chapter purposely made it misleading

In this situation of course she's panicking, who would not? But that doesn't mean it's okay to kill her because it's 'the best choice'. There were two ways to show mercy, and the other, nicer, way would be to give her a chance to live, to protect her. And that's what someone with power should do. I don't think Pauliana did wrong, but as a king he could have done more. At least that's what I would have done, I mean she is innocent and there is clearly a good way out of this situation. And no one knows how strong she could have been, there are people with trauma that still can live happy and so something important for the society.
But it's fiction, I know xD