Why lightsabers would be far more lethal than George Lucas envisioned

Research is an unpredictable process. Sometimes you end up making a really cool discovery that you didn't see coming. I recently uncovered a fundamental property of lightsabers (that's right - the awesome weapons from Star Wars) while doing my regular plasma physics research. I found that, while it is in theory possible to build a lightsaber, it's likely it would be the most dangerous weapon ever created - both for the perpetrator and the victim.