It's me again with yet another ridiculous question.
While in backwater villages and similar places your average adventurers can walk around armed to the teeth, doing their best impersonation of a Shield Guardian... what about big cities like Korvosa or Absalom? Is there no such thing as weapons control? Are all spells legal? Can I just buy a Charm Person or Acid Arrow scroll at the Ascendant Court? Is it okay to walk around with better equipment than all of the city guard combined without being a known gladiator of the Irorium? Or perhaps I'm just thinking too much by bothering with such nonsenses as a PC growing enough to start being perceived as a potential threat to the establishment?
All valid questions.
I treat it a little bit like the wild west meets ancient Rome.
You've got little backwater towns. Cowboys and ranchers and bandits and, well, everyone else if they want to, all walk around town with a six-shooter on their hip and a rifle in their hands, and nobody says a word.
Except in some towns, where the lawman is really a control freak (check out The Unforgiven) and demands all weapons be checked in to his supervision until you leave town.
Even so, if Doc Holladay headed back east to Chicago or New York, and walked down the street with his shotgun in hand, the cops would roust him in no time.
A middle ground is peace ties. Swords are wired into their scabbards, axes have a metal cover wired onto the business end, etc. It's not a perfect solution, as there is no way to "nerf" a mace, for example, but most weapons can be blunted. Usually it takes 5 or 6 rounds to undo a peace tie. So if tempers flare and weapons are to be drawn, well, there is time for mediation, reconsideration, or outright flight before they can become lethal. Some villages, towns, and even cities may allow strangers to carry weapons, but require peace ties or the weapon will be confiscated.
The ancient Rome part kicks in with the intrigue. Uneasy lies the head that wears a crown. Or a laurel wreath. Or a sheriff's badge.
When the PCs get a little big for the the locals to handle, they will have done one of two things.
Either they will have established a public identity as law-abiding heroes who protect the innocents, or they won't.
If they established that public identity, then nobody is likely to mind if they strut around armed to the teeth. Might even make most of them feel safer.
But if their deeds are questionable, if the locals feel that these adventurer guys may be just as bad as the local villains, or worse even, then those uneasy heads may start to planning and plotting and intrigue.
As to buying weapons, why not? No weapon is inherently evil. Swords don't kill people, monsters do.
Sure, some towns have anti-weapon laws, so in those towns, buying weapons may be very difficult. 3-day cool-down waiting periods, licenses required, magistrate signature on the writ of purchase, etc.
Everywhere else, weapons should be fair game.
Same with spells, mostly.
Almost every town has anti-magic laws. Nobody wants the town to burn down because some mage dropped a fireball on a cutpurse in the town square.
Advanced civilizations have well-defined laws that casting a spell on a citizen is equivalent to swinging an axe at his neck, and such acts are punished accordingly. And the old "it was just a detect curse spell" doesn't fly - even if it was.
But, as long as you don't go around town casting spells and causing problems, buying and selling the spells is usually legal.
Except for the obvious red-flag spells, like Animate Dead or Bestow Curse. Might want to shop for these spells very carefully.