Life in many parts of LATMA is nasty, brutal, and a whole lot shorter if you're not armed and dangerous. However, this does not extend to Bright areas - carrying any form of weapon in Bright zones (such as Corporate Center or Downtown) is not only close to impossible, but liable to get you into lethal trouble with MetSec. The technology used in the TUBE stations (and TUBE stations, regardless of destination, are always considered Bright for the purposes of security) may be assumed to detect virtually all forms of weaponry, so for the most part only magical methods of concealment will succeed. Use of a weapon in a Bright zone draws immediate, extremely prejudiced response.
Grey zones are more questionable. MetSec officers are much rarer, camera coverage far less common, and crime a reasonable probability. Heavy weapons will still result in severely negative attention, but security is liable to overlook simple forms of weapon such as knives or light firearms. However, they remain illegal both to possess and use - those who choose or are forced to do so are advised to vacate the area immediately afterward to avoid consequences.
Dark zones see very little MetSec presence, and except in the case of serious stupidity, most weaponry - both possession and use - will cause little comment (but sometimes retaliation). They're dangerous areas without formal rule of law, so personal security is largely in the hands of the individual.
Permits: Weapons permits are, for the most part, issued exclusively to security officers. Individual citizens (those with a legal SSN) may also be allowed carry permits for personal defense, but many Bright locations may require disarmament before allowing a person on premises, and MetSec response to any armed civilian is touchy at best. Since carry permits for civilians do not extend to TUBE stations, personal armaments tend to be restricted to the citzen's home territory.