"Ancient Europeans believed that if they ground up the bones of their greatest warriors or sacred animals and mixed them in with the iron when forging a sword, the sword would contain their spirits, making it stronger.

Little did they know that by adding in the ground up bones they were introducing carbon to the mix and creating carbon steel, which is much stronger than simple iron. So they were making their swords stronger by adding the sacred bones, just not in the way they thought they were."