What is the rarest lightsaber in the world?

Have you ever wondered about the most elusive and sought-after lightsaber in the galaxy? Imagine holding a piece of history that few have ever laid eyes on, a lightsaber so rare that it's almost mythical. What characteristics would this lightsaber possess? Perhaps it's crafted from a material so unique and precious that it's nearly impossible to find, or it belongs to a legendary Jedi or Sith Lord. The question stands: what is the rarest lightsaber in the world, and how does one even begin to acquire such a treasure?