That depends on why you think it's called a lightsaber...
It either means...
1) Lightsabers light up and area, therefore "light"sabers
or...
2) All of the weight of a lightsaber is in the hilt, thus making it not a heavy but a "light"saber.
As far as I can tell nobody knows for sure, everybody assumes 1 though.
<{POST_SNAPBACK}>
I would go for a sword that emitts light.