The below-mentioned weapons were used in Syphon Filter 3.
Glock 17 with suppressor
The silenced 9mm is the 9mm with a suppressor attached. This firearm is good for stealth missions and taking down enemies quietly. It is actually a Glock 17.
IMI Mark XIX Desert Eagle
The falcon is a powerful weapon; it can generally take an enemy out with one shot and is actually a Mark XIX Desert Eagle. The falcon mainly appears in the Hotel Fukushima.
The G18 is a machine pistol. It takes out enemies quick and it is very efficient. It seems to be a Glock 18 with an extended clip. Due to its blazing fast fire rate, players should be careful lest they be left defenseless during a reload.
Heckler and Koch MP5
Apparently a machine pistol, this is in fact a sub machine gun in real life called the Heckler and Koch MP5. It is best employed during close-quarters shootouts.
The .45 is a pistol that is more powerful than the 9mm but less damaging than the Falcon. The .45 mainly appears in the Costa Rican Plantation but is hidden in the other levels.
PP 19 Bizon
Yet another apparent machine pistol but this is actually a submachine gun. It fires at a fast speed and has a high ammo capacity. There is a butt at the end of the gun but since characters only hold it with one hand it is never used. It is actually called the PP 19 Bizon.
Magpul Folding Machine Gun
A weapon that is ironically the only PDW revealed to be a true SMG. The others, the HK5, Biz-2 and Skorpion are all listed as machine pistols. It is based on the Magpul Folding Machine Gun (FMG-9).
Spyder Skorpion vz 61
Only appears in a crate in the SS Lorelei. Ridiculously overpowered, it is in fact the Skorpion vz 61 and shreds through enemies in split-seconds.
A weapon appearing in various missions throughout the game. It is accurate and holds a lot of ammo. Strangely it has the same reload sound or recoil as a pistol.
An assault rifle that pierces through flak jackets, killing armoured enemies without the need for a precision headshot. Strangely it is used with one-hand. It is actually a SIG 550.
A rifle that is incredibly powerful; in fact it's an AKM.
The Steyr AUG possesses an X-ray scope allowing users to shoot enemies through solid surfaces. Possibly a reference to Die Hard, from which Syphon Filter in general draws its inspiration.
Silenced sniper rifle
The silenced sniper rifle is actually an AS50 with an EO tech scope. It is very significant on stealth missions and is great for taking out targets quick and without notice or danger inflicted on the player. It is what Logan uses in Hotel Fukushima.
Night vision sniper
The nightvision sniper rifle is an efficient but weaker sniper rifle. It is great for taking out enemies in dark areas but is the weakest sniper rifle. It has a nightvision scope and is actually the Dragunov SVD. The nightvision scope has the same nightvision sight as the nightvision googles in the game.
Heckler and Koch G11
The H11 is actually an assault rifle with a special scope. It is a special weapon that appears only in a few chapters. It can be found in crates and some fallen enemies. It is actually called the G11. It holds 300 rounds with a clip size of 50 rounds.
Mossberg 500 Compact Cruiser
The shotgun is a pump action weapon that is devastating in close-quarters. It is actually a 12 gauge Mossberg 500 Compact Cruiser.
Actually a Franchi SPAS 15, this is found in a few missions.
Daewood Precision Industries USAS-12
The USAS 12 is a rapid fire assault shotgun that is very strong. It was the weapon used by Gabe Logan to try to kill Rhoemer. The USAS 12 is the weapon of choice for Jason Chance as well.
An automatic shotgun similar to the USAS 12 but not as strong. It appears in only a few missions mainly found in crates making the weapon a special find. It is actually called the Heckler and Koch CAWS shotgun and appears mostly in all missions.
A less-than-lethal weapon with a red dot sight can be used on certain missions. Its maximum capacity is 5 rounds and it is best used to neutralise non-hostile targets without killing them. Despite its knockout ability aiming for the target's head will cause fatalities.
Holds 4 grenades and is the most powerful weapon in the game. It is handheld which would be impossible because of its blowback power and it has a butt which isn't used. It appears in mainly every mission and is used for dire situations. It is recommended for saving, because of its good use for taking out armoured enemies.