Divine Water was the creation of gods and could be used to instantly heal a person from wounds or undo curses.
As per the novel he had read, divine water was created when a righteous god infused their divine energy with water. If a god wasn't righteous, what they would end up creating following the same method of infusing their divine energy with water wouldn't be divine water. It would be akin to poison, harmful to all life.
In the Era of Gods, righteous gods were everywhere, thus divine water was also present in abundant quantities. However, in the current Era, which was the age of peace and prosperity, the only active righteous god left was Ahshun, meaning, in this world, only with his blessing could divine water be created.
Ahshun wasn't stingy. He would occasionally create divine water for his worshippers.
Ahshun was a generous god, but the same couldn't be said for his followers, the Ahshunites.
