Haha that was kinda sarcastic. Yes it's a sword made of blood.
It's about a half-dreamshade (=monster) boy and a dreamshade hunter girl with cursed blood living in a world where dreamshades are kinda like poltergeists etc. They chase some dreamshades but the show focuses more on the relationship between characters and worldbuilding. It's visually extremely impressive ("a TV show with movie budget") so it's worth watching even just for the visuals. Mostly criticized for the weird pacing, but I liked it a lot overall.