The Colt M1911A1 is a prominent pistol seen throughout the show, most notably by Worick Arcangelo and various criminals as their sidearm of choice. The former also carries it with a mounted suppressor when needed.
Heckler & Koch P2A1
A Heckler & Koch P2A1 was used by Worrick to summon reinforcements near the end of "Siblings".
IMI Desert Eagle
Several IMI Desert Eagle Mark Is are on display at Connie Raveau's gun shop at the start of "Naughty Boys".
Makarov PM
A Makarov PM is on display at Connie's gun shop at the start of "Naughty Boys".
SIG Pro
A SIG Pro pistol is seen on a newspaper in the middle of "Ergastulum". The details aren't clear to determine the variant type.
Taurus PT911
What appears to be a Taurusu PT911 is seen on display in Connie's gun shop at the start of "Evening Dress".
Tokagypt Type 58
A Tokagypt Type 58 is seen on display in Connie's gun shop at the start of "Evening Dress".
Walther P99
A few Walther P99s are on display at Connie's gun shop at the start of "Naughty Boys".
Walther PPK
A stainless Walther PPK is used by Gina Paulklee as her main sidearm, first seen in "Sanctions". They appears to be used with downer-based tranquilizer bullets to wear out Twilights.
Revolvers
Smith & Wesson Model 28
A Smith & Wesson Model 28 is the weapon of choice used by Daniel Monroe throughout the series.
Smith & Wesson Model 66
A Smith & Wesson Model 66 is seen in a gun case delivered by Nicholas to a client in the middle of "Ergastulum".
Submachine Guns
FN P90
A FN P90 is seen on display at Connie's gun shop at the start of "Naughty Boys".
Heckler & Koch MP5A3
A Heckler & Koch MP5A3 is seen on display at Connie's gun shop at the start of "Naughty Boys".
Heckler & Koch MP7A1
A Heckler & Koch MP7A1 with a Hensoldt RSA red dot sight is seen on display at Connie's gun shop at the start of "Naughty Boys".
Ingram MAC-11
An Ingram MAC-11 is seen on display at Connie's gun shop at the start of "Naughty Boys".
IMI Uzi
An IMI Uzi is seen on display at Connie's gun shop at the start of "Naughty Boys".
Assault Rifles
Colt M16A1
Colt M16A1s appear in "Land of Confusion" in an animation error instead of M16A2s in the hands of Paulkee Guild mercenaries as their main assault rifle.
Colt M16A2
What appear to be Colt M16A2s are seen in "Ergastulum" in a newspaper photo with Gaston Brown's mercenary forces as their main assault rifle and in the hands of mafia soldiers working for Monroe as their main weapon. One is possibly seen with an anti-Twilight rioter in a flashback sequence in "Thorn". Paulklee Guild mercenaries use them as their main assault rifle, first seen in "Land of Confusion".
FN SCAR-L
A FN SCAR-L is seen on display at Connie's gun shop at the start of "Naughty Boys".
IMI Galil
An IMI Galil-type rifle is seen on display at Connie's gun store at the start of "Evening Dress". There aren't enough details to determine what the variant is since both close up and far shots of the scene don't show any concrete details.
Shotguns
Benelli M3
A Benelli M3 with just a pistol grip was used by Delico in the middle of "Nonconformist" after he takes it from a dead mafia soldier.
Franchi SPAS-12
A Franchi SPAS-12 with a short barrel and pistol is seen in Connie's gun shop at the start of "Evening Dress". A full-size SPAS-12 is seen with a Paulkee Guild mercenary backing Doug near the end of "Land of Confusion".
Sniper Rifles
Remington 700
What appears to be a Remington 700 modified to have a pistol grip is used by an assassin during a gang war in "Nonconformist".
Grenades
M67 Frag Grenade
A M67 Frag Grenade gets thrown by an anti-Twilight rioter in a flashback sequence near the end of "Thorn".