Léon's (Jean Reno) signature pistols are Beretta 92FS's with compensators and in some scenes sound suppressors. A compensator reduces rising of the barrel during rapid fire by redirecting propellant gases. We briefly see Mathilda (Natalie Portman) assembling Léon's (Jean Reno) Beretta 92FS pistols although we never see her take a shot. The combination of a suppressor and compensator can be considered nonsensical because a suppressor is supposed to avoid the gases to escape from a shot and a compensator lets gases out which contradicts the function of a suppressor, but the threads of the suppressor clearly affix past the compensator cuts, canceling the function of the compensator. During the end shootout, one of Léon's Berettas features a two-toned finish, with a stainless frame.
Star 30M
The head of security for the Fatman keeps a Star 30M as his sidearm.
Several of the Fatman's (Frank Senger) guards are armed with IMI Micro Uzis. At one point he ineffectively wields one himself.
IMI Mini Uzi
The Fatman (Frank Senger) arms himself with a pair of IMI Mini Uzis after emptying his IMI Micro Uzi. He is held at knife point by Léon (Jean Reno) before he can use them. ESU members at the end of the film are also seen armed with them.
Beretta 93R
During Léon's (Jean Reno) opening hit, a pair of the Fatman's (Frank Senger) bodyguards are armed with Beretta 93R machine pistols.
Ithaca 37
Norman Stansfield (Gary Oldman) uses an Ithaca 37 with a tactical flashlight mounted on the pump forend, and fitted with a pistol grip while raiding Matilda's (Natalie Portman) house. Malky (Peter Appel) also uses an Ithaca 37 with an extended magazine tube.
Smith & Wesson 3913/3914
A tutone Smith & Wesson automatic pistol is seen in the hands of one of Stansfield's men. It appears to be a stainless Smith & Wesson 3913 frame with a blued Smith & Wesson 3914 slide.
Kimel AP-9
During the attack on Mathilda's (Natalie Portman) family's apartment one of Stansfield's (Gary Oldman) men Willi Blood (Willi One Blood) is armed with an Kimel AP-9 pistol fitted with a 20-round magazine which he uses to kill Mathilda's little brother.
Remington 870
Mathilda's father (Michael Badalucco) pulls a Remington 870 Slug Gun shotgun on Stansfield (Gary Oldman) and shoots him in the shoulder during the attack on his apartment, as well as killing another henchmen with a shot to the back. Despite being a slug gun, people are impacted by buckshot when shot by it. We also see a Remington 870 on the gun rack in the Fatman's house, and an ESU member is seen wielding one during the final shootout.
SIG-Sauer P226
A SIG-Sauer P226 is used by one of Stansfield's DEA agents Benny (Keith A. Glascoe) as his duty weapon. It has some sort of laser aiming module mounted under the barrel.
The actor who played Benny, Keith A. Glascoe, was also a real life NYC Firefighter. He died rescuing people from the South Tower of the World Trade Center on September 11th, 2001.
A suppressed Skorpion SA Vz 82 is wielded by one of Stansfield's DEA Agents (Don Creech) after Mathilda's family is killed. It can be noted as the .380 ACP model Vz 82 by its straight magazine, unlike the curved magazine of the .32 ACP Skorpion SA Vz 61.
Léon (Jean Reno) has a Ruger SP101 in his case among his collection of weapons. He gives it to Matilda (Natalie Portman) when telling her to leave and be a "cleaner" on her own, resulting in her walking to the window and emptying the gun (although she fires six shots when the revolver only holds five). Later in the film Matilda tries to see if Léon really cares about her, so she loads three chambers, leave two empty, and plays the very difficult version of Russian Roulette. Léon tells her he could hear that there was a bullet in the chamber (not likely), but she continues and nearly kills herself before he knocks the gun away.
Beretta 92FS Inox
Léon keeps a Beretta 92FS Inox in his case along with his other equipment.
Norman Stansfield (Gary Oldman) keeps a Smith & Wesson Model 629 revolver with a 3" barrel and unfluted cylinder as his duty sidearm. Stansfield's Smith & Wesson Model 629 appears to be customized or at least a rare, non-catalogued special production run. The standard and/or limited production, short barreled 629s usually have slightly shorter ejector rods (while the gun in the film's ends at the barrel). The muzzle is nicely crowned, too. It's done in a manner uncommon on factory-standard Smith & Wesson revolvers (and limited production runs), which means it was likely a customized & shortened Smith & Wesson Model 629 "Classic Hunter". Unlike the standard model 629, the "Classic Hunter" variation was a special production run made in limited quantities in the late 1980's/early 1990's. It could be had in carbon blue steel and in stainless steel, came with an unfluted cylinder (standard production 629s feature fluted cylinders) and had either in 6-inch and 8 3/8-inch barrel length with the full underlug. Since the 629 "Classic Hunter" Stansfield packs isn't in factory configuration, we can assume it has been further customized and shortened, perhaps to make it more concealable and lighter to carry all-day like an oversized snub nose.
Spectre M4
A Spectre M4 is seen among the weapons in Léon's gun case. In the extended cut version, we see Léon cocking the weapon, as Léon recognizes the image based on the sound of a weapon cocking a drug dealer's apartment, which is not actually a Spectre M4 itself.
Custom Springfield Armory M1911-A1
Mathilda's (Natalie Portman) pistol is a Springfield Armory M1911-A1 fitted with a compensator and loaded with simunition paintball rounds. She uses it to shoot a drug dealer during her first "hit", fitting it with a suppressor that cancels out the compensator like with Léon's Berettas. She brings it with her when she goes to the DEA building planning to kill Stansfield (Gary Oldman). It is assumed she has it loaded with live ammunition, since simunition would prove useless for killing. Willi Blood (Willi One Blood) refers to it as "Another Nine-Milley," slang for 9mm obviously.
Springfield M1911-A2 SASS
Léon's (Jean Reno) case is packed with a Colt M1911A1 pistol with a nickel finish and combat hammer fitted with a Springfield Armory M1911-A2 SASS upper conversion kit. This conversion turns the 1911 into a single shot pistol in a variety of calibers.
SGW Multimatch AR-15
Léon requests a rifle from Tony (Danny Aiello) to train Mathilda (Natalie Portman) on her long range sniping exercise. Tony had one of his workers go into the freezer and pull out an SGW Multimatch AR-15 rifle. Mathilda uses the rifle (loaded with simunition paintball rounds) in her practice "hit" on the jogging politician in Central Park. Simunition is a trademark for training ammunition produced by General Dynamics - Ordnance and Tactical Systems Canada Inc. of Québec, Canada. Simunition encompasses many types of training rounds, the best-known being the FX Marking Cartridge, or paintball round.
Simunition rounds are designed to be fired through police and military service weapons. Most simunition cartridges require slight modification to the weapon to ensure that normal service rounds cannot be fired during training and to simulate full recoil with reduced-pressure/reduced-velocity rounds for more realistic training. The prop itself is a heavily modified SGW Multimatch AR-15 and it's very unlikely it actually fired the simunition. Simunition is used only for CQB training, as there is no way any paint round could reach the velocity to hit a target at that distance.
The rifle is the old model SGW Multimatch before SGW turned into what is now known as Olympic Arms. With a 16" medium heavy weight barrel, shaved gas block, carbine length free floating aluminum handguard tube, and a Bell & Carlson AR-15 Thumbhole stock. It has blued 20-round magazines (the kind available in the early 1990s), a Harris Bipod, and a dummy short 'suppressor' for the end of the threaded barrel. The scope is a Burris with a 40mm objective lense, and sits on Weaver's tall see-through scope mount rings.
The Ruger Mini-14 GB-F is seen in the hands of NYPD ESU officers who arrive at Léon's apartment during the final shootout.
IMI Galil ARM
One of the ESU officers in the first team that enters Léon's apartment is armed with a IMI Galil ARM
MAS AA-52
The MAS AA-52 is utilized by the ESU team to launch a grenade into Léon's apartment towards the end of the film.
Glock 17
A Glock 17 is holstered on the ESU uniform Leon steals.
Armi-Jaeger AP-15 w/ False Grenade Launcher
The Armi-Jager AP-15 is seen in the hands of a few ESU officers after the big fight. This could presumably be the same fake grenade launcher in Besson's Nikita.
Miscellaneous
M9 Bayonet
One of Stansfield's men uses an M9 Bayonet to check the mattress. The M9 Bayonet is the standard-issue bayonet for the US Armed Forces.
Note cut in blade for wire cutters, when combined with notch on sheath.
Suppresors
Note the third suppresor from the right with it's abnormally long threading to bypass the compensator on Leon's Beretta 92FS.