I feel Hokuen dying to Shin's blade feels wrong.
Everyone gets the point, all the dead people before Shin, Riboku and Shin himself : No matter how strong you are, you can't lead humanity alone and by yourself.
Even if he looks like Hulk, Houken himself should be a sage. He doesn't just swing his glaive around, he is supposed to use plenty of time meditating and pondering about "the path" itself, and it's been many years since he was "beaten" by Ouki.
Not only Houken has not learned nothing in all these years, even in his dying moments he is still unable to understand the very only thing he has been doing in all his life.
Also, it makes no sense plotwise that someone who stands at the pinnacle of martial arts is unable to beat someone who is already half-dead. It's not just about power, speed or willpower, Houken should have plenty of technique and experience to literally face Shin with just his bared hands, or else this is quite disappointing for a chinese sage of martial fighting. He should be also able to use chi and breathing techniques like Kyokai does at a higher level, and he simply swings his glaive with power like a moron.
Godamnit, he even beat Kyokai who is more nimble and faster than Shin who is a true genius using over 100% of her own capacity.
Back to the point. Around the time Shin has taken 20 of his mountain cleaving blows while fighting back, he should have just already found his answer. He is not supposed to just beat people around, he is supposed to ponder and understand what he doesn't for the sake of human evolution, if he dies, it's a loss for humanity, if he kills Shin, he fails to understand what he lacks.
I feel the elegant way of going about this, was for Houken to concede halfway the fight and leave the battlefield forever, either because he has finally found his answer or because he needs to change his way of finding the path.
I mean, he was already at the peak of martial arts when he fought Ouki, and has been wasting years in the mountain achieving nothing while shouting "I AM THE BUSHIN".
For a character that has been around for 10 fucking years of serialization, not only does he leave as a complete buffoon, he leaves a bad aftertaste because the one absolutely unbeatable character of the series lorewise, has been beaten with nakama power.
I never really expected anything from Houken himself, but I expected more from the author.