The Blood Princess and the Knight - Vol. 12 Ch. 402

[MangaDex]

 

[monkey123]

There is Garen, but where is his spin to win technique?

 

[Kanade0021]

The captain was killed without fighting

 

[manga_joggle]

So I'm guessing that the mysterious blonde is Bai Jin. If you look back at chapter 327, she looks the same with her armor on. And that would explain why the blue sword allowed her to use it.