I give this a 4.5/5

With a final blow, we see the close of this part Blackwing Series. I love this series. The representation is varied, and done with care and respect. I enjoy the found family trope that has built throughout the series. The characters have really grown together in understanding and friendship. I love that there is no romance between the principal characters, just friendship, leaning towards a sibling style relationship, especially with the confirmed age gap. The more minor of the core characters, Hylas and Aketa, get a bit more screen time, showing the healing and growth the teens have done. Their tight sibling relationship is so sweet, even with Aketa still struggling with the reveal of the last book. 
Ontiku continues to be my favorite character, who really leans into the old grumpy gay trope. I love his aside comments, and the peak further into his background we got in The Slain Princess. This finale did make me cry some, but more often than not, I was just angry on behalf of the titles Princess, and the other victims of the villain R. How could one person be so hateful. I really like the wrap up on this arc of finding R, and ending their reign of terror, while giving us a firm confirmation that the story will continue. The final reveal for Jinua that I had been suspecting for the last three installments was very satisfying as well.   The only real downside to this book for me is that it's really gory. More so than the others. It is to expected with a fantasy series revolving around necromancy and war, but it's a lot in some moments.