If I understand correctly you’re compared the demo video in the blog with content we’ve shown in trailers. The blood from katana hits is fairly straight forward in Ghost, it’s a combination of deferred ribbons and deferred billboards, no meshes. We generate runtime normals based on the edges of the erosion so the normal edge follows the eroding shape. Some blood comes from the target being hit and some comes off the sword as it travels, it’s a mix of both sources.
The main reason the blog blood looks different is that the effect was designed to work with the velocity of the katana, so to get a demo working I’m actually faking a velocity in a direction and I ended up disabling the ribbon sections. The streaky bits you’re referring to are probably the ribbons that got disabled, they show up in normal gameplay. Hopefully that helps explain it!