The TFA Visual Dictionary clarifies that the saber was salvaged by "someone" in the industrial depths of Cloud City, and that Maz has spent centuries collecting "countless" relics of great importance from across the galaxy, solely to protect them. Same source confirms that Maz herself is strong with the force, and exceptionally adept at sensing the galactic ebb and flow of dark and light, but opted not to walk the Jedi path.
So either that "someone" who scavenged the saber was Maz herself(perhaps it 'called' to her in a similar manner that it called to Rey), OR it was scavenged by someone who brought it to Maz because they knew it would hold great value to her.
But will Disney ever actually give us the full story? Yeah, probably at some point... But it will likely be told in a novel or comic, me thinks. It's not really an important plot-point to the films. /shrug
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Last edited by Galan007 on Mar 29th, 2018 at 01:45 AM