using your own blood would kill yourself. Someone who has the skill to learn bloodbending also has to hte ability to use common sense, and leave their blood in their body. Also, I can imagine it would be extremely painful to pull blood out of your body without any wounds.bloodspear uses ur own blood as you weapon, and i imagine the more blood u have the bigger the weapon and more damage, the more u bleed the more blood ul have for ur move, and since u dont bleed in minecraft without a mod i just use ur health bar as a reference to how much blood uv lost....u have to think open mineded and creative