Why make a light saber if you can harness that kind of energy?
Why cap the "lazer" or whatever you decide makes the beam?
Id just make it a lazer, then you can dice any jedi at 300 meters away!
Let's talk lightsabers. Ah, lightsabers. When I first saw Star Wars, I was 17 years old, and I thought they were laser beams. But that doesn't make any sense because a laser beam wouldn't come to a point after a few feet. Also, the laser wouldn't be visible unless there was a lot of dust in the air to scatter light and illuminate the beam. Plus, laser lightsabers would pass through each other like flashlight beams, which wouldn’t make for a very fun fight. So I think plasma is a better candidate. This ionized gas is made by lightning, is what the sun's made out of, and is even used in plasma TVs. You can contain plasma using electric and magnetic fields, which exert inward pressure to match the plasma's outward pressure. This means you could make different shapes, like a lightsaber–esque cylinder. But there are some problems: You couldn't create a tip, and plasma would leak and vaporize the skin off Luke Skywalker's hands. And as with a laser, you couldn't fit all the necessary machinery to generate the plasma into a sword handle. Plus, the beam would need to be millions of degrees and far denser, in terms of energy, than anything we have now. But if somehow you could do all that, sure enough, the lightsaber would cut through metal and bone. The fields containing plasma would repel other lightsabers, so they would work like what you see, except it would radiate a great deal of heat, about as much of the sun. Jedi would have really bad sunburns.