I didn't think about it in these terms back when I was playing the game in the early 90s, but now it comes to me as coming down to players choosing to embrace or ignore the conventions of the genre.
Limiting the discussion to what is seen in the films, we see Luke quite able to fool with his light sabre the instant it is handed to him, and we see Han able to use one to slice open a Tauntaun on Hoth. The actual use of the weapon is one of manual dexterity. Its use will be somewhat mundane, however, as the user will not be able to do the cool tricks they have seen in the movies.
To use one like a Jedi uses one (prediction, telekinetic throwing, blocking blaster bolts, etc) requires the ability to use the Force.
With these assumptions in place it is hard to say that a character cannot just pick up a light sabre and go. However, in the groups I played the game with, no one did this who was not a Jedi.
Being in Tune with the Living Force (Trust your genre, Luke)
The reason was simply that we felt it was a weapon tied to the Jedi. We felt they were not available on the open market, and we preferred to use weapons we could get better use of. In other words having my Outlaw and the other non-Jedi characters wander around with light sabres did not fit the genre. Sure it was possible, it just wasn't something that was done.
If this is enough of a problem for you that you want to create house rules to prevent it, I would recommend speaking to the players about that directly, and citing how it is not really in the spirit of the franchise. Just because a thing can be done, does not mean it will be done. This is a part of the roleplaying aspect of the game.
Not for sale at any price (Made by hand, custom orders only)
Going beyond what is explicit in the films (although it is referred to by the Emperor), we agreed with the idea that a Jedi makes their own light sabre. Unless they were to lose one in combat, have it stolen, or be defeated and the weapon taken, there was simply no way for one to come into someone else's hands. If this idea is a part of your saga, then it really reduces the likelihood of non-Jedi having them at any point.
This is just a reduction, as if a player wants one badly enough they will go out of their way to nuke the first Jedi or Sith they come across.
Everyone gets cut (Hokey religions and ancient weapons)
If you are not above a little realism in your Star Wars, then the concept familiar to blade students everywhere that 'everyone gets cut' can help limit the field of potential light sabre users to just those who have the courage and the dexterity to do it with a reasonable chance of success.
This also is a means to reduce their use, through fear of personal injury. Although the rules do not support a lot of detail in the death and dismemberment department, this roleplaying aid can greatly enhance the mystique of light sabres and make playing a Jedi worth the hassle.
Guilt by Association (Isn't that a Jedi weapon?)
As the weapon itself is an iconic representation of the Jedi Order, who are outlawed and under an execution order (death by Vader) by the Galactic Empire, drawing attention to oneself through the use of such a weapon can be a great hook to get the story moving into high gear with detention cells, torture, escapes, chases, and other Star Warsian fun~
Consequences for action are nice as they put choice in the hands of the player. Rather than getting into a "I don't want you to do that" situation if that would be a problem in your group, you can limit the use of light sabres simply by making them logically, and socially problematic to use. Luke was willing to draw attention, live away from society, and fight the Empire head on. Plus, he was a Jedi. Are you?
When diplomacy fails (Shut up, Goldenrod)
As with any discord at the table where interests, enjoyments, intentions, and the like come into conflict communication is always the first step in resolving it. The suggestions above are intended to be used in conjunction with establishing what the genre of the saga is, which aspects of Star Wars the whole group wants to explore and which aspects they do not, how much realism there should be in terms of consequence (Luke lost a hand, Ben died, Lando got kissed by that lippy pilot, Chewie never got any pants, every custodian in both death stars was atomized, Jabba was strangled in his own ride, etc), and what play style (mission oriented, sandbox, scenario-based, campaign-based, etc) is to be used.
Each person should contribute ideas about what they do and do not want to be a part of the game - this includes the GM. If non-Jedi using light sabres bothers you to a great degree, express that clearly in the simple terms that it impinges on your ability to have a good time with the setting.
If they counter with 'just wanting to have a cool imaginary toy' and 'what's the big deal, anyway?' you have an impasse.
If the players do not care or think you are going too far in feeling that using an elegant weapon from a more civilized age when not a Force Sensitive is a problem, it might be a good idea to consider their point of view. Their lack of consideration for yours notwithstanding it never hurts to reevaluate your own position.
If you are the GM and you still want to stick to your guns on the issue, then I recommend choosing to continue the game, choosing to keep quiet about them using light sabres unsafely, and follow through on sensible reactions from the universe: NOT vengeful ones; that leads to the dark side. The dark side has no retirement plan.
- Do not allow cool Jedi sabre tricks without the Force. The rules
support you on this.
- If they operate where there are troops or other law enforcement
personnel, and get spotted using light sabres, have them be
investigated within the normal abilities of the NPCs assigned to the
- Do not offer the devices for sale, and put them in the hands of those
who should have them. What happens after that is Story, not Problem.
- If they demonstrate to violent people that light sabres are cool and
they get a reputation for using them effectively, they should come to
expect reasonable counter-measures from the groups who hunt them
(Boba Fett's wrist grappling hook attack) and for the devices to be
looted if they get captured.
If you are not the GM then your options are more limited. If you want to play a by the book Jedi, and you are outclassed by the other characters the traditional approach is to just suck it up (Watch Luke get his butt handed to him by life, the universe and everything in Empire) until they finally get in tune with the living Force. If this does not sound like fun (being the slow starter with a big finish is not everyone's cup of Jawa Juice) then you are really asking yourself if the fun of the game outweighs the frustrations. If no, then don't play. If you are gaming at a con as you say, there is a lot of other stuff to do with fewer hassles.
Closing Music (In this case, the Sandcrawler theme)
In a certain sense, if the group is wanting to build a Star Wars saga of their own, with you in the GM's seat, you have an equal right to contribute to the saga which unfolds as they do. Sometimes that means saying "No" and sometimes that means making compromises. In any event, fun is the name of the game. Star Wars came to us as 'A New Hope' so it doesn't do to let it get you down~
If you are a fellow traveler on a wild ride in a galaxy, far, far away then try to connect with them and appeal to the sense of shared fun. If that fails, consider other options.