There are 9 different Weapons each if them with a unique part:
-Lead Pipe, your standard start Meeleweapon
-Crowbar, stronger the the Lead Pipe goo to crush skulls or Crates
-Pistol, Weak in Damage and Speed with normal Attackrange but can be improved by several mods which you can buy for it
-Shotgun, Good spreading Damage but slow speed and not much Range
-Tommygun, Attacks as fast as you Finger can push the Hotkey has also higher Damage then the Pistol and a large Magazine
-Grenade Launcher, Fires Grenades with high Firerate which explodes after a few seconds and the Target Place and deals some splash Damage
-Flamethrower, Ver low Range even lower then the Shotgun but High bruning Damage which burns the Target for several Seconds
-Rocket Launcher, Very high Splash Damage and good Fire Rate the Rockets explodes just like the Grenades at the target Location after a few Seconds
-Heavy Machine Gun HMG, Fires 3 Shot Bursts with some Cooldown between them with High Damage and High Range also can be improved by a Mod
You can find/buy some different Items as well:
-Ammotypes, Each Weapon uses their own ammo except for Pistol and Tommygun which shares the same Ammo you can find or buy lots of these and you need them for good.
-Questitems, Some of them can be found and some you will aquire troughout the Game from Chracters.
-Medpaks, Are instant healing Packs which recovers your Health.
-Armors, Same as the Medpaks but recovers your Mana which is based on Armor Value.
-Cash$, This one is found in small amounts or big Bags from Safes You need this more then anyting else to buy Weapons, Items, QuestsItems and Mercs.