
First of all, the grenades don't hold a slot in the player's arsenal, you must bind a key in the Customize Controls section in order to use it.
00 - Frag grenades
Infinite projectiles that you toss around, those when hitting the ground, or when sticking to a surface(it happens, don't worry), will explode, causing furious damage to any living soul next to it.

Chainsaw - The Chainsaw is the most powerful melee weapon that you will ever have in your hands. Though, it's attacks don't cause monsters to give you extra melee rage points. You must decide if you want more points, or kill enemies faster before using it.

Colt M2911 MK.2 - Your standard pistol, and your best buddy until you find another weapon to use. it's accurate, it's fast, and overall a good weapon, but also it's damage is bad against bigger enemies. You can use it to get rage points from smaller enemies though, shooting them and then punching them with the alternate fire - a quick punch

RAVEN Security Revolver - The .88 cal revolver used by some security planetary forces. It hits like a bus, good for bigger and meaner enemies, can be used for the same purpose as the handgun above, but, it shares the ammo with the AMR Sniper Rifle, which means that your ammo with this gun won't be so easy to get. Make every shot count.

KSW-616 Pump Action Shotgun - Used for general combat purposes, this weapon is the perfect balance between spread and accuracy, being perfect both at close range, and middle range.
It also have a grenade launcher embbed to it, the impact grenades explode when hits a target. otherwise (i.e hitting walls) it will probably bounce around before detonating itself.

Riot Control Shotgun - The full auto shotgun, used to control big crowds of demons during teleportation tests. It's good to damage and fire rate, though, the spread on this gun is considerably higher than other shotguns, making it more suitable for close quarters.

Double Barreled Shotgun "1-2 Deadmaker" - A strange but very powerful double barreled shotgun. Reverse engineer always failed when tried to replicate such a strong gun, the UAC employees calls it [Redacted]

RAVEN PCW - A 7.62×45 assault rifle equipped with a red reticle, it's the definitive balance between fire rate, accuracy and zooming.
It's bullets also rip through enemies, making it a powerful weapon for mostly occasions.

Heavy Enforcer MK.2 H.A.R - A Heavy Assault Rifle, that instead of firing a 5.56, or a 7.62, it fires a .50 cal bullet, of high impact, because when it comes to killing demons, the caliber you fire is never enough.
This rifle also have a rocket launcher as a attatchment, which means that you can fire missiles using the secondary fire.
Different from the Raven PCW though, it's bullets stop after hitting a target.

UAC "Mobile Turret" - Created by the UAC, those are a minigun-LMG hybrid, which are similar to defense turrets.
Though those are much more lightweight, allowing, for example, regular Marines to carry them for defense against "Big guys."
As primary fire, it shoots at a slower fire rate some high impact bullets, instantly, and as secondary, the weapon spins the barrel before firing at a very high fire rate.

M41-LRCW - LRCW being "Long Range Combat Weapon", is a powerful sniper rifle that have high accuracy, made for long range combat, it comes equipped with a powerful scope. The ammo it holds, explode on impact, so, even if you miss the target, if you hit close enough, the explosion radius can still damage the enemy.

UAC M45 Plasma Generator - A plasma machine gun. This gun is a prototype made by UAC in order to contain the "bigger ones", those being Hell Knights, Barons and Mancubi. It works simple as possible, You can fire it till the overheat meter reaches 100, or, until you run out of ammo.

Thunderbird MK.2 Energy Cannon - The "Thunderbird" is a Heavy Impact energy cannon, it is used to combat against heavy armoured enemies, or, the "Tough guys", probably the Cyberdemon units, or to control crowds of Barons of Hell. It's a hard hitting gun, though it consumes a lot of ammo
Not explaining the Fists and the BFG because they are pretty simple.