When the RPG first came out in 1987 there was very little information on the Jedi order as a whole. The prequel trilogy wasn't even on the drawing board back then and the glut of Star Wars novels had yet to be written. In a way, the setting was kind of a wilderness—where I, as GM, had to blaze a few trails and make some decisions as to how things that weren't explained actually worked. One of those things was: exactly what defined a 'Jedi Knight', at least from the angle of game skills and skill levels. What I came up with worked well enough in my campaign so I'll share it here for anyone who cares.
First of all, I narrowed down the defining skills of a Jedi. These turned out to be:
4) Lightsaber (I later just evolved this into Melee)
The first four are no-brainers. The latter two were included for specific reasons. In the game (and indeed in the movie), mention was made of one of a Jedi student's final tasks being the construction of his/her own lightsaber. And as I recall, lightsaber technology was also included on the list of skills presented for various characters in the RPG sourcebooks.
Jedi-Lore would represent the philosophical teachings of the Jedi order along with a bit of background as to the history of the order and tales of former Jedi. It is a distinctly 'mental' skill that seems to fit nicely with the other more physical and metaphysical ones listed above.
As far as the skill levels that represented a Jedi Knight I was at a bit of a loss. There wasn't a whole lot to go on except the stats of the feature characters as they were provided in the various source books. So I had to extrapolate and came up with this rough system.
In order to be considered a Jedi Knight you had to have at least 7D in Control, Sense and Alter, 7D in Lightsaber and Lightsaber-Tech and around 5D in Jedi-Lore. To beginning characters especially this seemed sufficiently 'mega'.
In order to be considered a Jedi Master you had to have at least 9D in all those initial skills and 7D in Jedi-Lore.
This has worked pretty well in my campaign, though in fleshing out my current roster of Jedi Knights and students I have tweaked it a little. Now, to be considered a Knight you need an AVERAGE of 7D across all three Force powers (ex: you could have an 8D control, 7D Sense and 6D Alter). The same average goes for Masters as well, working out to 9D.
Working backward from these numbers, the ranking system goes something like this:
5D+ Junior Knight
11D+ Senior Master
I've seen D6 stats created for Jedi from the prequel trilogy on a couple other Web sites, but those seem a bit low to me. They had 'average' knights with 3 or 4D Force skill levels. From the way the Jedi fought in the movies, I'd say they'd be just a bit better than that—if not a lot better. On the flip side, even with 7D skills, a Jedi is not invulnerable. As the players in my campaign well know, a squad of Stormtroopers firing in a volley is a serious threat. Again, I think this was borne out in the movies. When the Jedi had surprise or backup or were fighting small groups of opponents they were able to wreak havoc. When faced with serious opposition (such as in the Geonosis Arena, or when Order 66 was given) they can be taken out. So in my book, the 7D level balance works out pretty well.