Was talked about by what I presume is one of the artists here: VFX of Ghost of Tsushima - a recent blog - #10 by mattv
May help guide you.
I also found an article online that says: “Besides adding blood to character models, every attack creates a particle effect with thousands of blood droplets and blood strings. Each of the droplets lands on nearby geometry, and in the water it even disperses into clouds that move with the current.” https://blog.playstation.com/2021/01/12/how-stunning-visual-effects-bring-ghost-of-tsushima-to-life/
Though most of the video content is missing, but here’s the blood tech video specifically:
https://www.reddit.com/r/PS4/comments/kwd702/video_ghost_of_tsushima_blood_particles_tech/