Let's talk about violence.
I'm not getting into firefights or space combat go read Books 4 & 5 if you're into that stuff. Similarly I'm not getting into conventional firefights. There've been enough of those since Book 1. I want to talk about citizens of the known worlds and associated moons. What do they do when forced to rely on their own fortitude and fists? How are their responses shaped by their cultures?
The most obvious code for Traveller referees is the Law Level. Quick review:
LL Restricted Weapons
0- Nukes (Starport law level)
1- Body pistols, explosives, poison gas
2- Portable energy weapons
3- Automatic weapons (machineguns)
4- Light assault weapons (assault rifles, SMGs)
5- Personal concealable firearms
6- All firearms except shotguns
8- Blade weapons controlled
9- No weapons outside the home
A- No weapons
First of all starports take a very dim view of people torching their facilities and bystanders with fusion guns. Also having a weapon does not mean you have carte blanch to use it. Common sense applies here: do you want someone using a firearm around a refueling station? Though people can be walking arsenals disagreements in a port may often be handled with fists or blades just to avoid entanglement with the authorities. Tip: if you're carrying a nuke hit that mugger over the head with it.
Body pistols have an extreme restriction attached to them. What's the difference between carrying a revolver under your jacket and a body pistol? The body pistol is mostly plastic and ceramic construction designed to pass most sensor scans and is regarded as a terrorism or assassination tool. Small pistols in the same style but made of metal would not be restricted until LL 5. A society allowing Body pistols must be extremely libertarian, in disarray or aware they can't find the darn things anyway.
Body pistols might even be preferred over other weapons to settle disputes since they require you to be brave enough to get fairly close to your target to have a good chance of smoking them. Note this restriction may be extended to other hard to find weapons: ceramic blades, super spy gadgets etc.
Laser weapons are near and dear to me. They are restricted at a fairly low law level as well. The reason is that they make a hash of most common forensic techniques. Shoot a guy with a rifle and the bullet may be retrieved given precious information. A beam just burns or blasts its target. While I'm sure science will find ways to derive details from a laser crater I'll wager a bullet is far more tangible. Also that's without discussing micro-tags inserted into the propellant and bullet itself. By TL 9 or 10 a box of rounds might be imprinted with the time and place of purchase and your credit card number. Lasers may also suffer from the same stigma as body pistols resulting in banning at much lower levels.
Automatic weapons refer to machineguns and other squad support weapons. We can probably include VRF gauss guns and such in here. The weapons can inflict huge amounts of collateral damage and imperil innocents. Again, toting around a machinegun doesn't mean people are going to react well to you hosing a mugger. See my tip regarding nukes.
At the higher law levels people are denied firearms and must rely on blades or their fists. LL 8 indicates blade weapons are controlled. This could mean restrictions on concealment or length. It can indicate that types of weapons are restricted by social standing and other factors. Polearms for soldiers of police, swords and such for nobles, short bladed weapons for peons etc (why am I hitting on you? You are bearing a rapier my good man! Hey, put the body pistol away! I'm leaving.)
Some planets may allow dueling. The requirements may be calling a person out and going to a safe area. It may require going to a mandated arena to avoid harming others (Machineguns at forty paces!)
High law levels may also result in the locals learning martial arts and fighting with improvised weapons. Extreme weapons restrictions had exactly this effect in Japan. Taking a poke at a local might result in a mixed martial arts battle. Locals could also rely on ordinary items for defense. Screwdrivers, hammers, saws and other tools can easily be applied to bloodletting and provide an alibi if you're clever (an electrician can be expected to carry a screwdriver, a CPA can't. The CPA could hit you with his briefcase.)
Snub pistols deserve mention. This is the one weapon in Classic Traveller that does non-lethal damage. A case could be made for easing restrictions on it except it not only fires tranquilizer rounds; it fires high explosive or armor piercing rounds. I'd allow a tranq. only variant to be restricted at LL 6 or even LL 7. The major concern is can the tranq rounds be modified to fire lethal toxins or the other explosive rounds? That would determine to restriction. In crowded environments the snub pistol might even replace the Shotgun at LL 6.
Finally for your consideration: the local culture may frown upon violence. People living at high law levels especially may be conditioned to call upon the police when wronged (this is great if they show up.) In this case they may also have contests to settle arguments that are dangerous in and of themselves: playing chicken with air rafts, attempting re-entry with vacc suits or prying your fingernails off until one of you cries 'mercy'! So chose when and where you start a fight carefully.