True, but theoretically we could construct an energy field that surrounds the user, his opponent, and all other living things.

Just don't try and fight drones.

Also, wouldn't anything like the traditional lightsaber glow constitute losses of photons from the crystal structure? That might become a problem.

1 meter plasma beam made by a Chinese company. 200kW, 200°C~15,000°C

http://i.imgur.com/JlN7gYY.jpg