compact yoke
I'm taking inspo from Mugen with this idea. When you kill someone (or a strong npc) with a breathing style or blood demon art, there could be a short voiceline for it.
It could differ based on how brutal or calm a style/blood demon art is. Some voicelines could be inspired (obviously not directly copied) from the show.
For example, water breathing could say something like "rest in peace". Flame breathing could say something like "burn to ash" (kind of corny, but could be cool if the va is skilled enough). You get the gist.