Ka Nan arc dragged too much, and the ending is kinda unsatisfactory. I think Boru's suicide is a huge factor in making the conclusion feels that way to me. Like, is there no better way to end his character without making it feels like such a wasted potential? There's also the fact that the rebellion relied waaaaaaayy too much on Chinmi. Sure the rebels picked up some slacks here and there, but their plan would just fall apart after 30 minutes or so if Chinmi wasn't there. And let's not talk about Pu Shin.
Navy arc started too slow and the recruitment chapters are just so boring. I know that it's for setting up the plot, but the first half of this arc is too formulaic for my taste. There's also a missed opportunity of not having Tan Tan vs Sie Fan. The arc really picked up by the second half tho. I really wish Chouryuu played a part much earlier, he's an interesting character to the point it feels more like he's fighting for more screen time instead of Kaion.