Luke’s lightsaber was originally blue in the “Return of the Jedi” promotional material to reflect the hue in the previous films. As Lucasfilm creative executive Pablo Hidalgo explained to Vanity Fair, “In that universe, at that time, as far as anyone knew, lightsabers were red or they were blue.” However, green made for a more striking visual contrast between Tatooine’s blue sky and yellow sand. Besides, Luke lost his original lightsaber, so the switch worked. Hidalgo pointed out that “as much as we like to mythologize why it’s green and what that all signifies, sometimes there are very pragmatic filmmaking reasons behind these things.”

For instance, Mace Windu’s purple lightsaber in the prequel trilogy was all because Samuel L. Jackson wanted it that way in order to stand out more, despite fans claiming that it’s because he’s dabbled in the Dark Side of the Force. There are also some canon works that have hinted at symbolic meanings behind the lightsaber colors. The Jedi Temple guards in the animated “Star Wars: The Clone Wars” series, for example, wield yellow blades, the same color as Rey’s lightsaber seen at the end of “The Rise of Skywalker.” That might denote its users’ roles as guardians and protectors of the Order. In addition, the Darksaber in “The Mandalorian” series has a whole Excalibur-like backstory behind it. 

Then again, these do look pretty cool, so who’s to say what’s behind a deeper meaning?