The original banning of Streel from doing business on Clarion came about from the government's order to all mega corps to demilitarize their operations. Streel’s violation of this resulted in the original 20 year ban.

Clarion has further instituted gun licensing and bans on certain weapons that are considered military in nature. All defensive suits and screens are allowed but weapons with a rate of fire of 3 or higher, heavy weapons, high damage, or explosive ordinance are considered military. Military, police and paramilitary personnel can purchase much of this with their ID card though most organizations allow their personnel to requisition what they want or need within limits.

The availability of weapons varies greatly depending on where you are in the system.
On Clarion “tame” weapons like semi automatics, needlers, and stun weapons are readily available as well as tangler and smoke grenades. Lasers can be purchased that will only discharge 1 or 2 SEU per shot though it’s a simple procedure for technicians and beam weapons specialist to remove the power governor and allow it to shoot at the full power setting. Explosives are very tightly controlled and tracked. There is of course a black market but that can be difficult to access and markups of 50-100% are not unusual.

On Clarion Station in orbit the situation is a bit looser with many ships coming and going. The same laws apply but the Royal Marines don’t confiscate banned weapons if they’re declared and locked in a weapons locker. Permits for carrying “ship safe weapons” are fairly easy to obtain providing no criminal record (record check is only Clarion’s data base). Ammunition that could endanger the safety of the station cost more and is harder to buy but most legal weapons are freely available. The black market is a little more open as deals can go down on ship and transfers of goods can happen in a number of ways. The black market here runs generally at 25-45% mark up.

On Planaron Ore Processing Stations (POPS) things are quite different as none of the licensing laws apply. The station was built on the gutted Planaron asteroid after Space Mines Inc purchased it from the Crown. Over time it has developed into a rough community of wildcat prospectors, low-life and less savory spacers. It is often referred to as a wretched hive of scum and villainy. Here the black market is the open market.
Most traders will keep certain wares out of site if Royal Marines have entered the station preferring to avoid drawing too much attention to them. It is often possible to buy weapons here that are vastly marked down but these either have seen heavy use and abuse or they may be flagged in a police data base somewhere.