Mark Hamill has had a long career in entertainment, but he's first and foremost known as Luke Skywalker. His role as the hero of Star Wars has has cemented him in pop culture and film history, and he recently reprised his role in Rian Johnson's Star Wars: The Last Jedi. As such, he's seen plenty of lightsabers in his day, including his original blue one, and the green saber from Return of the Jedi.
Luke Skywalker's blue lightsaber is probably his most well known, as its had a long life in the Star Wars franchise, beginning with Mark Hamill wielding it in A New Hope and Empire Strikes Back. A Hollywood auction recently announced it would be selling Luke's original lightsaber, but Hamill took to Twitter to warn potential buyers and fans. Check it out.
While not insinuating the lightsaber was a fake, Mark Hamill wanted to make clear that there were a ton of props used throughout George Lucas' original trilogy. As such, there isn't one lightsaber that the actor used in either movie. So get the full picture before you shell out cash to become a bonafide Jedi.
Mark Hamill's tweet is one of the many times the legendary actor and voice performer interacted with his Twitter followers. Hamill is very generous with his time on social media, often taking to Twitter to communicate directly with his generations of fans. In fact, he even bantered back and forth with fans in the responses to his tweet.
Lightsabers are a prop that have mystified moviegoers since A New Hope arrived in theaters back in 1977. And as such, there's been merchandised versions of the weapon for decades, becoming a bit more lifelike as technology developed. But there's nothing like the real thing, which is exactly why some fans are willing to pay out the wazoo for a piece of the original Star Wars trilogy. That is, if the prop is legit.
Some Star Wars fans have even gone so far as to create their own lightsabers. While this is mostly done by lighting and engineering, there was a recent fan lightsaber that actually produced a blue flame-- looking and functioning closest to what the Jedi use in the franchise. While it's likely quite dangerous, you can't deny how hardcore the Star Wars fandom is.
Luke's blue lightsaber has been a connective tissue between the original trilogy, the prequels, and the Force Awakens era. It originally belonged to Anakin Skywalker aka Darth Vader, before he eventually fell to the dark side in Revenge of The Sith. Obi-Wan gave it to Luke in A New Hope, although he eventually lost it (along with his hand) during his duel with Darth Vader in Empire.
Maz Kanata somehow acquired the saber (let's hope that's explained in Episode IX), and eventually gave it to Rey when she traveled to Takodana with Han Solo in The Force Awakens. The Last Jedi saw the saber broken in half in Rey and Kylo's conflict, and it's unclear if we'll see it again, or if Rey will create a new one.