Immediately following the conclusion of the Jedi's war with the Lost Tribe of Sith and the destruction of the dark side entity Abeloth, a member of the Force deity family of the Ones, the Jedi decided to arm the future generations against Abeloth's eventual return.
Luke Skywalker knew that the dagger had been used to kill other members of the Ones during the Clone Wars, and though the Jedi had no idea where Mortis was, it was their only hope in permanently destroying Abeloth.. As such, Skywalker sent the Quest Knights on a mission to find the Mortis monolith that led to the planet Mortis, where they hoped to be able to find the dagger.