The lead robber during the beginning of the film, holds a Italian made Parvini 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 (Jason Statham) 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 SG 552
A SIG SG 552 is used by Frank (Jason Statham) when he is checking shipping containers for the Chinese prisoners.
Steyr AUG HBAR
A Steyr AUG HBAR is used by one of Wall Streets' assassins to shoot up Frank Martin's house. What is noteworthy is that all the shooters are using 5.56x45mm weapons, which would not be the preferred weapon to shoot at Frank's stone house. The 5.56mm round is small, fast and light and would not have the penetrating power to punch holes through thick timber or stonework.
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).
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.
SIG-Sauer P226
MP5K
One of Wall Street's thugs at the house uses an MP5K to try to kill Frank.
Colt M4
Used by a Thug.
Smith & Wesson Model 60 Snub
An old style Smith & Wesson Model 60 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.
Mossberg 500
Smith & Wesson Model 500
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.
Rocket Launcher
One of Wall Streets' assassins uses a mocked up launcher that 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.