WEG could have made it up. A lot of ear material was fabricated whole-cloth for the RPG line, and this could be one of those things.
-EF
I was simply trying to answer HappyDaze's question (quoted above) based on my knowledge of relatively old SWRPGs and the sources available to me. My main point was that there actually is some published material that supports this [house] rule, hence it is more than just a "Myth" as HappyDaze described.
I suspect it was included to dissuade non-force-using PCs from using lightsabers, which is perfectly fine reason for the mechanic as far as I'm concerned. Whether it was either invented (i.e. it is not based on canon) or adapted (i.e. it is based on canon) for that purpose is beyond me. I won't, since I certainly can't , deny that the rule could have been fabricated whole cloth by WEG, since I have no knowledge of such an event occurring any canon.
Follow-up on that, the WEG rule doesn't discriminate between force-users and non-force-users; Anyone missing the difficulty by 10 or more injures themself. This part is widely house-ruled in games so a bad attack roll doesn't totally ruin someone's day and character, and is frequently moot since most force-using 'saber wielders are using the Lightsaber Combat ability which gives a good boost the Lightsaber skill when used by most force sensitives.
However, I like the rule, and include it in my games. Basically, if you don't have a force rating, Despair rolled on a Lightsaber combat check can be used to deal the attack's damage to the wielder. It provides a simple, mechanical answer to the question "why everyone isn't using a lightsaber?"
If you don't like the rule, fine, don't use it. But it is based on LucasFilm approved material. I'm not going to get into another debate/discussion/argument/fight about "what makes sense" for lightsabers. SW is soft sci-fi, so the thing does whatever the thing needs to do.
Edited by LethalDose