Do you mean the blood that's created from shooting the player, or just blood scenery?
- The players blood is in Soldat>Gostek-gfx>ranny. This is what you see on the player after being shot.
- There is also Soldat>Sparks-gfx and there are a few files here that correspond to blood. These are called "blood" "lilblood" and "splat" and they can be either .bmp or .png.
- And, if you're making a map, most of the prominent blood sceneries start with "m_blood" And they can be found in Soldat>Scenery-gfx.
Good luck. I hope this helps. And please say if this is one of the first 2 solutions, because If so I'd like to move it to the modding section.