I have been thinking for quite a while now and everyone thinks plasma is what makes up the light saber blade. At first I thought no way. But then I looked into it. Plasma being the fourth state of matter is extremely hot which makes it a good fit for the job. On the other hand it is a gas and takes huge amounts of power to create. It is also a gas not a hard solid. Knowing this I decided that the handheld version would be physically impossible unless you can make a nuclear reactor the size of soup can.
What you would have to do is make a magnetic felid that forms a tube according to your blade. Then you would have to make plasma that is propelled out of the "emitter". Since plasma is repelled by magnetism it would in there form a "blade" shape. I think this is in our reach within the near future. :o :o :o