Ways of removing blood stains on wood depend upon its treatment.
Clean the blood stain with a brush soaked in white vinegar sprinkled with baking soda.
If this is not enough, use bleach.
Remember to rinse after removing the stain.
Remove excess stain. Wash the wood with cold water and soap.
If the wood is still stained, sand the stained polish down and vacuum, wax and buff.
Wipe fresh blood stains with a damp sponge and then rinse again and dry the varnished wood with a rag.
If the blood stain is old and embedded, dab the wood with a cloth dampened with a mixture of French polish, linseed oil and methylated spirits.