TV’s Frink said:
For most of these situations there are many plausible explanations (see the lightsaber on Cloud City discussion),Indeed. Because it is entirely plausible that Luke’s lightsaber fell down the main shaft at Bespin; got sucked into one of those, what, dozens of exhaust ducts; got caught up somehow, thereby preventing it from falling out and down to the fiery surface of the gas giant; was then found by someone or some thing in the duct (or wherever the duct may dump out or collect); recognized by that someone or some thing as something worth not throwing in the junk pile; then taken to – out of literally millions of planets in the galaxy – Maz Kanata, where she put it neatly in a box. In a box, to be given, someday, to someone, whom she met literally 10 or 15 minutes earlier.
Indeed, that is, in your words, an entirely “plausible explanation.”
I will allow it is possible that the lightsaber was not destroyed, but it is much more difficult to concede that it was delivered to Maz, who merely relegated it to an unlocked box in her storage room, from which she later intuitively knew it to be calling to Rey and so made of it a gift without question…