Lovecraftian. Creppy.

Yep :D

Blood and Veins aid in combat. The blood seems to form a blade, and my guess is, that it chips away, and tiny droplets sprays toward the attacker, trying to get into their eyes, blinding them. The veins may have the strength of the undead in them, and might even grapple the opponent's wrist or neck and snap it, or just do whip-like attacks for low damage like 1d2 for each veins.

The sustaining effect is quite nice. The wielder gets stabbed on the neck by a sword or knocked out by a mace on the face and the shock makes them unconscious, but the sword keeps grabbing to their arms, and tries to heal the wielder. In busy battle, this prevents the sword getting lost or be stolen (looting) and the sustaining/healing effect may restore the wielder back into fighting state (or well enough to gulp a health potion or two) maybe in under a minute or two...and surprise surprise, the dead man stood up and has a second chance at helping out the party...maybe even manages to do a sneak attack/backstabbing even.