Well, if you don't use Lemur, and you want to do it with plain old FPSC, then just edit the character's FPE script.
Here is the part of a WWII Officer's FPE, change...
;decals
decalmax = 2
decal0 = red
decal1 = blood
to ...
;decals
decalmax = 2
decal0 = red
decal1 =
...By omitting the 'blood' from decal1 and leaving it blank you have no blood effect for that character.
After you build his game you can set get the blood back defining decal1 = blood, like it was before.
You only have to change the FPE files of the characters that are being used for his game.
NOTE: FPE not FPI, these are
Entity scripts, not
Intelligence scripts, for those who didn't know.
The FPE is usually in the same folder as the entities other files. (BMP, X, DDS, etc. in entitybank)