For a long time, people believed that Gods were not able to die. Even by the hands of another God, such a divine Being only casts off their physical shape and revives sooner or later with a new shape. The Soul of a God is of such power that they cannot be absorbed without being devoured by the God.
As technology and Magic increased in everyday life, so did the imagination and inventive prowess of the people. They experimented with weapons and the arcane arts and found many ways to harm and kill Beings of various strengths and powers.
It was Niamh, the Grotesque Artist, that found a way to fight off the Gods. In secrecy, she carved nails out of bones and infused them with arcane powers. The results are specially made weapons to destroy Souls. These nails have to be made individually for the victim and are matched to counteract the Aura and the individual powers of the target's Soul.
Since Niamh was sealed off, there were no reports of any Coffinnails to be seen, though it is known that she made one nail for each of the Gods and kept them safe with her. It is unknown whether she was sealed off with her or not.