Do the following jobs to get corresponding items and weapons. You may have to repeat jobs but you will eventually get the item associated with the job.

Beat Up Rival Gangster (1e):
.22 Pistol (2A 0D)

Collect Protection Money (2e):
Butterfly Knife (2A 1D)

Rough Up Dealers (2e):
Brass Knuckles (2A 2D)

Rob a Pimp (3e):
.9mm Semi-Automatic (3A 2D)

Take Out a Rogue Cop (3e):
.45 Revolver (3A 2D)

Perform a Hit (3e):
Tactical Shotgun (3A 2D)

Destroy Enemy Mon Hideout (5e):
C-4 (5A 2D)

Kill a Protected Snitch (5e):
Stab-Proof Vest (2A 5D)

Bust a Made Man Out of Prison (5e):
Automatic Rifle (4A 4D)

Fight a Haitian Gang (6e):
Semi-Automatic Shotgun (5A 4D)

Smuggle Across The Border (7e):
Armored Truck (4A 8D)

Repel the Yakuza (13e):
Grenade Launcher (14A 10D)

Disrupt Rival Smuggling Ring (15e):
50 .50 Caliber Rifle (16A 11D)

Invade Tong-Controlled Neighborhood (25e):
Armored Car (14A 15D)

Sell Guns to the Russian Mob (25e):
RPG Launcher (20A 12D)

Protect your City against a Rival Family (35e):
Bodyguards (8A 25D)

Assassinate a Political Figure (35e):
Night Vision Goggles (5A 16D)

Exterminate a Rival Family (40e):
Napalm Attack (25A 9D)