The lead robber during the beginning of the film, holds a Italian made Pardini PC9 pistol. It is a large match grade target pistol, used in European IPSC style competitions and somewhat unlikely weapon to be carried by a bank robber.
Frank Martin pulls a Bruni 8mm M1911 Blank Pistol from the shoulder holster of Wall Street (Matt Schulze). Later Lai (Qi Shu) uses it to threaten both Wall Street and her own Father.
Beretta Cougar Inox
Used by one of Kwai's bodyguards.
Glock 17
SIG-Sauer P226
Walther P99
Seen inside Frank's fishing tub, also where he keeps several grenades and his SIG SG552 and spare magazines.
Smith and Wesson 5906
On the film's cover, Frank has what looks like a 5906 in his left hand and a Beretta Inox in his right.
Revolvers
Smith & Wesson Model 29
Two of the bank robbers in the beginning of the film used Smith & Wesson Model 29 revolvers. One is blued and the other is bright nickel plated.
Smith & Wesson Model 629 Customized
Mr. Kwai (Ric Young) pulls out a Pre "Performance Center" customized Model 629
the gun is too small to be a 44mag I own a 6in 629 either a bad prop or a 357/41
Smith & Wesson Model 637
An Smith & Wesson Model 637 Snub nosed revolver (with black plastic grips) is carried by Tarconi (François Berléand) who offers it to Frank who uses it in his escape. Tarconi later offers the same revolver to Frank for his assault on the shipyard, whereas Frank declines, instead showing that he has bigger firepower for the mission.
Unknown French Police Revolver
A stainless Snub nosed revolver is carried by the French National Police, but it is hard to identify.
Manurhin MR-73
At least one of the French police has a Manurhin MR-73 Gendarmie Revolver.
A SIG SG 552 is used by Frank when he is checking shipping containers for smuggled Chinese people.
-Anyone have any idea what the attachment on this Sig is?
It is a "single point" occluded-eye sight. These were 1st introduced in the late 1960's I think this one is a weaver made model, Armson also made them but I remember those to be smaller.
Steyr AUG HBAR
A Steyr AUG HBAR is used by one of Wall Streets' assassins to shoot up Frank Martin's house.
Customized M16A1
The third assassin who shoots up Frank Martin's house. It appears to be a standard M16A1 with an unusual A2-ish forearm and a strange upper section that looks like it's trying to copy a Beretta AR-70/90 in general shape and style (especially the forward slant of the carry handle).
I want to say the unusual thing mounted on top of the M16 is a very old school laser aiming device.
SIG SG 543
Used by one of Wall Streets' assassins to shoot up Frank Martin's house. His SIG SG 543 has a 40mm launcher attached. The launcher for the SIG SG 550 series is the SIG GL 5140 grenade launcher however this is not one of those launchers. It looks closer to the M203 style.
Ruger AC556
During the battle inside the Bus depot, one of Wall Street's thugs fires a customized Ruger AC556 (the full auto version of the Ruger Mini 14) at Frank Martin. The rifle has a Choate™ aftermarket flash hider extension as well as a flashlight mounted to the barrel.
Steyr AUG
During the battle inside the Bus depot, one of Wall Street's thugs fires a standard Steyr AUG at Frank Martin.
M16A2
During the battle inside the Bus Depot, one of the assassins fires a full auto M16A2. (The real M16A2 is a three shot burst weapon, so this is a 'fake' M16A2, or an M16A3 (which was the A2 with the A1 fire control group that was issued in small numbers to Naval personnel). In some shots there are wear marks on the barrel that resemble the cutouts of an M4, however upon closer inspection, they are wear marks from either a non-standard laser or flashlight mount.
Submachine Guns
Heckler & Koch MP5K
One of Wall Street's thugs at the house uses an MP5K to try to kill Frank.
Mini Uzi
Beretta M12
Some of the French National Police who open the truck's container have Beretta M12 Submachine guns slung.
Shotguns
Remington 870
Wall Street during the highway chase uses a Remington 870 shotgun.
Mossberg 500
Other
Fake Matador Rocket Launcher
One of Wall Streets' assassins uses a mocked up launcher that somewhat resembles the Matador Missile Launcher, however, the method of launching is completely different. It loads (and reloads) in the rear like an M1A1 Bazooka and fires 'self guiding' rockets that appear to be able to make 90 degree turns in flight.
Later the man firing the launcher pulls out the 'Special' munitions - a standard M20B style rocket with a cartoon shark face painted on to indicate it's 'special status'.
Notes
During the attack on Frank's house we can see a lot of 'spent' rounds falling to the ground. The extended tip and star crimped ends indicate that they are 5.56mm blank ammo.