I passed the How Lightsabers Work link around to some friends of mine, and a lively discussion ensued.
For your entertainment and/or edification, here is the discussion...
[G] That's always puzzled me. If the energy shaft were round, it would have to vaporize a one or two-centimeter swath through anything it cuts, resulting it potentially violent explosions as so much solid matter is converted directly to superheated gas.
[P] True, I suppose.
[G] Which leads to the obvious next question, how does the blade orient itself to the cut? I.e. how do you keep from spanking the target with the flat part of the blade? Is this part of the "gyroscopic" action mentioned in the article? Is the wielder not free to swing willy-nilly in an omnidirectional manner? Or is the perceived width of the blade merely the result of a glowing energy field around what is really a molecule-thin cutting beam? So many questions...
[P] Ummm... I'm guessing you've never used a sword. Or, more particularly, a saber. I don't know how to explain it other than to say that it's easy to tell by feel if the hilt is right-way-up in your hand, and the rest is all in your wrist action. The blade feels like an extension of your arm, and the blade is on the same plane as the back of your hand - the motions are instinctive, whether you're chopping, blocking with the flat of the blade, or stabbing.
[G] But the lightsaber *hilt* is round, with radial symmetry if you ignore the occasional knob or odd protruberance. The thing doesn't even have a contoured handgrip! In any case you're comparing ancient Earth battle gear to highly-advanced technological weaponry from (let's face it) an alien civilization. It's apples and oranges. Furthermore, it's apparant from the movies' historical documents that there's no planar orientation required for a lightsaber swing. It's just willy-nilly wherever.
[P] I don't know what that 'gyroscopic' stuff is supposed to be about, unless it means that the thing resists twisting (rotation about the long axis of the blade). That feature would help you make nice straight cuts, but I'd hate to have to fight the 'gyroscope' to twist the blade every time I reached the end of an arc and had to turn the edge back on target. Metal sabers have their own quirks, though - at the end of a stroke, you "fly" the blade around in a tight turn like an airplane wing before swinging hard back the way you came.
[P] As to why the lightsaber blade looks like a round column from any viewing angle, my guess is that the blade is unraveling the air molecules next to its surface and making them glow. Across the width of the blade, there are a lot of particles-formerly-known-as-air doing their best to radiate heat and get the hell away from the blade, so you'd expect a bulge of high-energy glowing crap to be at its thickest against the center of the blade. Off the 'edges', though, the superheated plasma has more room to escape and dissipate into the surrounding medium.
[P] Apart from being able to deliver obscene amounts of energy on target, though, lightsabers are 'teh ghey.' They make noise, and they light up the whole d@#n area. The beauty of a real cavalry saber is that you can pop out from behind a tree and take someone's arm off - QUIETLY.
As for me, "ancient weapons are no match for a good blaster at your side, kid"!
See also: Sci-Fi