The Pact Worlds have, within living memory, fought a number of fairly devastating wars (in particular, against the Veskarium and the Swarm), and the outbreaks of new wars are entirely possible. Thus, most governments will probably encourage citizens to be proficient with weapons and practice with them on a regular basis - this gives them a greater reserve of people they can draft once the shooting does start. That being said, not all weapons are equal and not all are equally acceptable in all circumstances. Here is my best guess:
Single-shot sidearms (pistols and the like): Unexceptionable under most circumstances, except in ultra-secure or ultra-formal settings or where there is a real danger of damaging highly sensitive equipment (the bulkheads of most space stations - including Absalom Station should not be easily penetrable by random shots, but the guts of the local life support systems might be another matter). Places where people regularly consume mood-altering substances that might make them more aggressive (such as drug dens) or where the clientele is exceptionally violent (such as certain bars in the criminal underground) might also restrict all weapons.
Single-shot longarms (rifles and the like): Unproblematic in "frontiers" and similar areas where attacks by monsters, bandits and the like might not be necessarily common, but are always a possibility.
Automatic weapons: Generally only acceptable in military-controlled regions or where attacks by hostile entities occur on a regular basis, since there is a lot of risk for collateral damage. Plasma weapons will be seen with suspicion for much the same reason.
Explosives: Like automatic weapons, acceptable only in areas where attacks are frequent - since those can cause a lot of collateral damage.
Melee weapons: Knifes can be classified similar to sidearms - besides using them for protection, they are also common tools (especially in frontier regions) Larger melee weapons (such as swords) generally say one of two things about their user:
- "I have put in serious work at dealing out violence up close and personal" (since it takes a lot more training to become proficient with them than simple sidearms), or
- "I am a violent thug who relishes carving up others up close".
Such melee weapons likely have a similar legal standing to single-shot longarms, but wearers will be viewed with more suspicion since they might belong into the second category (for how to avoid that perception, see the next section).
Finally, space stations or similar habitats with closed life support systems will likely place additional restrictions on plasma and similar weapons that can quickly start large-scale fires, as well as chemical or biological volatiles (gas grenades and the like) that can foul up the enclosed atmosphere - since unlike with planetary atmosphere there will be no reservoir of fresh air and no place to flee.
Player AdviceSo what does this mean for player characters who want to keep using their favorite toys, no matter what the circumstances are? While avoiding all forms of arms control is probably not feasible, player characters can probably mitigate much of it by following these guidelines:
Be respectable. While the Pact Worlds don't have instantaneous interplanetary (let alone interstellar) communication, their communication systems will still be vastly better than those of Golarion in the Pathfinder area. In other words, news of the player characters' exploits will get around (especially if one of the PCs was brave or foolish enough to take the "Icon" theme). And how they acted during their exploits will determine a lot how much leeway the authorities will give them regarding their weaponry. If they consistently helped and defended other people, then they can get away with a lot. ("You carry what kinds of explosives with you? Oh, wait... didn't I see you in that video where you took down a purple worm attacking our colony with those? No, go ahead - I am sure you will use them responsibly, although I hope they won't be needed..."). On the other hand, if they harass, intimidate, or even attack other people on a regular basis they will be seen with a lot more suspicion - even if there is no outstanding warrant on them at the moment.
A corollary to this is that they should think twice about intimidating others with their weaponry ("Please hand over your weapons before entering this establishment." - "Make me!"), since this can effectively represent a declaration of war against the local authorities. You entered their turf and demand that they back down instead of following their customs, and even if they back down you will have made a new enemy since you have just reduced their authority in the eyes of the other locals. And most local authorities cannot afford to back down in front of such a challenge - whether the authorities are actual law enforcement or the local mob. Sometimes such a challenge is appropriate - especially if the local authorities are brutal tyrants - but the players should consider the implications before issuing it.
Appear respectable. Many organizations in the setting - law enforcement, armed forces, orders of knighthood, explorers' societies and so forth - have members who wear weapons as part of their duties yet are not viewed with (much) suspicion for it. This is because they wear uniforms or insignia proclaiming that they are part of a larger organization - and, presumably, they will have to answer for any misbehavior to their superiors within that organization. They can even get into many ultra-formal settings where weapons would normally not be allowed if he weapons are considered to be "part of their uniform".
And this approach can serve the PCs as well. If they cannot or will not join one of these established organizations, they could found their own. Just like the "professional adventuring parties" of bygone ages they could form their own chartered company (providing mercenary services, or exploration, or any other profession that describes what the PCs do as a group) and design a snazzy uniform that all party members wear while "on duty" (or at least "on display"). And even if this is a pure legal fiction, others will rest easier in their presence knowing that the PCs are "responsible" to some larger organization (which could, in theory, be sued for any damages the PCs cause).
Even if the PCs are not part of an "official organization", they can still attempt to dress "respectably" - as opposed to "street scum and vagabonds".
Finally, while there are methods of circumventing arms control - such as glamered weapons disguising their true nature - the PCs should not rely on them all the time. If they get caught, then most people will assume that they are still using them and search them more thoroughly or even deny them entry in the future.
Game Master AdviceSo, how should GMs use weapon control in their game?
First of all, don't use weapon control to screw the PCs over! If the PCs have to hand over their weapons before being allowed into a certain facility, then restrict the weapons the bad guys have access to as well. Perhaps their attempt at smuggling weapons in can be discovered by the PCs (in which case they get to use the contraband for the fight), or they might be as limited in what they can bear as the PCs. Furthermore, if the PCs hand their weapons over, make sure that they get them back from the owners afterwards. Otherwise the PCs will constantly focus on how to smuggle their favorite toys into adventure locations, which will likely derail the adventures.
Secondly - as pointed out earlier - make past PC behavior matter! If the PCs have been acting responsibly with their weapons in their past, cut them some slack with what they are allowed to pack (although this might mean that the authorities come to them with dangerous problems. To which I say: Adventure plots!). Conversely, if they have been misbehaving take not of that - and have the local authorities quote these incidents at them as justifications for why they are treated differently.
This doesn't even mean you have to take their weapons away, or refuse them entry. Instead, after a long discussion about past incidents where the PCs misbehaved (make them squirm!) you can have the custom official frown at them and say the following:
"Okay, here is what I can do. I am really not all that comfortable with you walking around with all those weapons. But if you, [most-respectable-looking PC] sign this form that you take responsibility for the behavior of your... associates, I am willing to let you through. Oh, and I also need you to pay a bond of 5000 credits [scale as appropriate]. If you leave without causing any... incidents, you will get the money back. Otherwise it will be used as a down payment on any damages you have caused."
This way, the PCs need to police their own if they want their money back - which is far easier than have NPCs do it. More fun for the GM as well...
To sum it up: Yes, some form of weapon control will exist in various places, but it should be used appropriately - it can make for interesting complications, but not deprive the PCs of their toys all the time.