Try using deeper shades of alizarin crimson or 'Rembrandt's' burnt alizarin crimson, cadmium red deep, and the lighter shades of cadmium red. For blood-staining on clothing, which darkens to brown quite quickly, try adding thinned-down sepia to the reds/crimsons. Try to avoid overdoing it, or making it too bright.....you'll soon get to see what looks right to your eye. I'm sure a little experimentation will get results you can be happy with. Blood is always a contentious thing on figures, even if in reality it was apparent in copious amounts on the battlefield (along with large amounts of the other contents of bodies of men and animals). Have a look at various battle action paintings to see how various artists handled it.....rarely does one see the 'claret' overdone.