Just finished a re-read and the ending still lands for me, but it's definitely not what you'd call a clean, happy wrap-up. Ikta gets what he wants in a way—Yatori survives and the immediate war ends, but his victory is pyrrhic. He loses his position, his health is wrecked from the 'cursed sword' effects, and he walks away from the empire entirely with Yatori, living under assumed names. The country itself is stable-ish under Princess Chamille, but the cost is immense. Torway and Suya are still around, serving in the military I think. Matthew... I had to go back and check, but yeah, he makes it too. The core circle survives, which is rare for a war story this gritty, but they're all profoundly changed. Ikta becomes a ghost in the system he saved.
What sticks with me is the final image of Ikta and Yatori leaving everything behind. It's bittersweet because he achieved his strategic goal of ending the war without catastrophic loss of life on his side, but he had to sacrifice his own future and legacy to do it. There's no parade for him, no recognition. It fits his character perfectly—the lazy genius who never wanted glory, only results—but man, it's a quiet, almost melancholy ending compared to the epic scale of the battles. I've seen some fans wish for a more triumphant conclusion, but this feels more true to the series' cynical yet pragmatic heart.