These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Badass Decay: Rio in the anime, after — in fact, because of — her very Badass introduction, becomes anIll Girl but never goes back to her initial level of badassery even after she's discharged from hospital.
Base Breaker: Half the fandom finds Hiyono annoying, the other half think she's one of the best characters ever made.
Tear Jerker: There are lots of them, especially by the last three books of the manga (Kanone and Hizumi are good at these). Also Charlotte's backstory in Alive.
Wangst: Everything Ayumu says about how he can never compare to Kiyotaka, how there's no hope in ever surpassing him though there's a reason for it, considering what Kiyotaka is,and how destiny always wins because Kiyotaka says so.
Iron and Stoic Woobie (Eyes Rutherford. Despite all the mess that just keeps happening to him, from being cursed to having his best friend turn on him and try to kill him and then dying, he's just not going to stop hoping, and cries all of one single tear in both the anime and the manga. Ayumu as well ; though he angsts a lot in the beginning, he gets pretty awesome at overcoming it all by the end of the manga.)
Ayumi refuses to let himself die, even after all the quite harrowing events of later chapters. He's more or less using this to guilt-trip the rest of the Blade Children to stop moping, live their lives, and Screw Destiny. The way it works out makes him into more of a Messianic Archetype.