The Sacred Knife is a knife that came from the heavens. When it landed on an unknown planet no one knew where it came from. They asked everyone and no one knew. Eventually they asked all of the Kais if it came from them, but it didn't come from any of them. The spirit of the Elder Kai took a look at it and said ,"It has the essence of God." and walked away. After that people started calling it The Sacred Knife.
The Sacred Knife is very special. It is a double bladed knife that can kill someone instantly with one side of the knife, and can heal even a dead person. It can only heal someone that is dead if it has been 24 hours since their death. Anymore than they won't be able to heal. Also each person can only use the healing ability and the ability to kill someone immediatly once. After they have used the abilities it is just a regular knife for that person. However for everyone else it is still powerful. Potatsos had found it while he lived on Planet Knuffle but lost it on his way to Earth. No one knows where it is now.