One of Priya's bodyguards in Mumbai, India is armed with a Beretta 92A1 in "Wanted". Michael uses one near the end of "Pay-Off" when he goes with Nikita to Dubai to raid MDK Industries and save hostages inside the compound.
Beretta 92FS
Ryan (Noah Bean) uses a Beretta 92FS briefly in "Set-Up" before Birkhoff disarms him. In the same episode, Michael uses it as his main sidearm before Sam disarm him of it in Mumbai. A few Shop agents pursue a wounded Ryan armed with 92FS pistols in the middle of "Bubble".
Beretta 92FS Inox
A Beretta 92FS Inox is shown in a flashback sequence in "Wanted". The fake President Spencer uses a 92FS Inox to shoot her herself in the temple at the beginning of "Set-Up". Nikita uses one in "Canceled" as part of her plan to destroy the Shop permanently.
Beretta Px4 Storm
Wilton Police use the Beretta Px4 Storm in "Wanted" and Nikita takes one after she returning to America from Canada. Michael uses it to threaten FBI Deputy Director Matthew Graham in helping Nikita escape near the end of the same episode. In "Set-Up", it's the main sidearm used by CIA agents operating the Mumbai blacksite with Alex taking it from a CIA agent after disarming him of his sidearm. Ex-terrorist Ramon Esquivel (Simon Kassianides), who now works for the Shop, uses a Beretta Px4 Storm as his main sidearm in "Pay-Off". Ryan takes one from a Shop agent in "Bubble", using it before running out of ammo. Trevor Adrian keeps one in a drawer, which he uses against Nikita in the middle of "Canceled".
The Px4 Storm later becomes Nikita's sidearm in the season.
Beretta Px4 Storm SD
Nikita appears to switch from her standard Px4 Storm to a Px4 Storm SD when she leads a raid on MDK Industries near the end of "Pay-Off", now being her new sidearm. Amanda takes one from a Shop guard and uses it to execute everyone in the control room after she learns of Nikita's raid on the building.
CAA Tactical RONI-G1
MDK Industries security guards in Dubai appear to be armed with CAA Tactical RONI-G1 with possible Glock 17s mounted since they were never fired near the end of "Pay-Off".
Glock 17
Nikita uses the Glock 17 in "Wanted", as do FBI agents in a dream sequence. Virginia State Police officers carry holstered Glock 17s in "Dead or Alive". A CIA agent at the Mumbai blacksite near the end of "Set-Up" uses a Glock, including fake Pakistani soldiers planted by the Shop in "Pay-Off". Nikita uses one in the same episode after killing its owner, Another second generation Glock 17 is used by a Shop agent and by a couple of Marines in "Bubble". Colonel Peter Slocum's double (Joshua Peace) uses one in the middle of "Canceled".
Glock 26
A suppressed Glock 26 is used by a Shop agent in Geneva in "Pay-Off".
Sonya (Lyndie Greenwood) can be seen with a chrome plated Zoraki 914 in "Set-Up" (S04E03). Alex uses one in "Pay-Off" and "Cancelled".
Zoraki 925
Shop agents use Zoraki 925s, and Alex takes one after she disarms a Shop agent in "Wanted", and uses it for several episodes.
Unknown
Revolvers
Chiappa Rhino 20DS
Amanda uses the Chiappa Rhino 20DS with a chrome finish as her handgun of choice in Season 4.
Chiappa Rhino 50DS
Owen/Sam (Devon Sawa) uses a Chiappa Rhino 50DS as his preferred weapon in season 4. An gunman in Mumbai, India has one before Sam disarms him and shoots him with it in "Set-Up". Michael later disarms Samm and holds it on him later in the episode.
Submachine Guns
Heckler & Koch MP5A3
FBI Agents in "Dead or Alive" are armed with Heckler & Koch MP5A3s outfitted with railed handguards. A Pakistani soldier on a ballistic missile TEL is armed with the MP5A3 in "Pay-Off", and Ryan uses an MP5A3 when the team storms MDK Industries later in the episode.
Heckler & Koch MP7A1
CIA SOG operators uses Heckler & Koch MP7A1s in "Dead or Alive" when they capture Alex in her hotel suite.
Heckler & Koch MP5K
Michael uses a Heckler & Koch MP5K in "Pay-Off" when he and Nikita go after a hijacked balistic missile.
IMI Uzi
Priya's bodyguards in Mumbai, India use IMI Uzis in "Wanted" and "Dead or Alive".
Assault Rifles
Colt M4A1
Virginia State Police officers guarding the Graham residence in "Dead or Alive" are armed with Colt M4A1s outfitted with railed handguards and vertical foregrips. US Marines surrounding the Adrian estate in "Canceled" are armed with M4A1s.
Norinco Type 56
At the end of "Canceled", Michael and Nikita witness a guerrilla fighter handing a Norinco Type 56 to a young boy.
SIG SG 552
Ramon uses a SIG SG 552 with a dot sight as he oversees the hijacking of a Pakistani ballistic missile in "Pay-Off".
Zastava M70AB2
A few of Priya's bodyguards in Mumbai use Zastava M70AB2s, first seen in "Wanted" after a human smuggling exchange goes bad.
Zastava M70 (Unknown Variant)
Custom AR-15
Micheal's custom AR-15 makes its final appearance in "Canceled", the series finale, as Alex (Lyndsy Fonseca) uses it to cover Nikita.
Shotguns
Benelli Nova
Alex hands Nikita her old Benelli Nova Tactical from Season 2 at the end of "Bubble".
Remington 870
FBI agents in a dream sequence are armed with Remington 870s at the beginning of "Wanted".
Sniper Rifles
Barrett M82A1M
A US Marine Corp sniper team in "Canceled" is armed with a Barrett M82A1M when they conduct recon at the Adrian estate Nikita and Alex had seized in the middle of "Canceled".
Heckler & Koch G3SG/1 (modified as a PSG-1)
Nikita uses a Heckler & Koch G3SG/1 visually modified to resemble a Heckler & Koch PSG-1 in the middle of "Dead or Alive" where she and Michael conduct a false flag operation to discredit the fake FBI Deputy Director.
Machine Guns
Browning M2HB
A Browning M2HB is seen mounted on a US Marine Corp Humvee at the start of "Bubble".
Rheinmetall MG3
Pakistani troops guarding a Pakistani nuclear-missile base in "Pay-Off" are seen manning a machine gun nest with a MG3.
Rocket Launchers
Norinco Type 69
A Pakistani gunman in "Pay-Off" is seen armed with a Norinco Type 69.