You get one weapon....

[Fallingwater]

Vash the Stampede's revolver/angel arm.
Can be used as a gun to stop the occasional baddie, as a low-power beam weapon to stop a group, or as a full-power planet-destroyer to cleanse the evil once and for all.

 

[Belthalmel]

The Jabberwocky Eye Staff.

I see your eyestaff and raise you a Blunderbuss. Seriously though. I'd take the Lionheart from FF8

 

[[Gavo]]

]Well, since everyone else is doin' mechs, I'm going to blow the rest of them out of the water. Into orbit.

The Warlord Titan (W40K). Bring it on, hell.

Spoiler

Haven't played the ultranerd card in a while, but... that's not an Imperator titan, that's a Warlord titan, the next smaller mech class below the Imperator. The Imperator, one of two subclasses of Emperor titans, is an actual castle on two legs:

Spoiler: Enemies of the Imperium, you're fucked now...

As for me, if we're talking about a regular-sized effective weapon (with infinite ammo, of course), I'm going with the plasmacaster, coupled with a Yautja mask and targetting laser. The last thing the demons of hell will ever see are the three red dots of doom.

Whoops. I was looking for an epic picture, this one was the only good one. But yeah, I know the difference. Although I have seen some badass ones, just not any art.

 

[Rooster893]

Plasma rifle from Quake 3 Arena

 

[NEVRINx54]

The MIRV, and unlimited shots.

i second that.

 

[Maze1125]

The GDI orbital Ion Cannon.

 

[Kyd Wykkyd]

whatever bayonetta uses when her her clothes fly off.

 

[Yeager942]

The lighting gun from District 9.

 

[JWAN]

Colt Python.

Gorgeous handgun, a real work of art. Hardwood inlaid grip with a nickle plated barrel. That was before that stupid gold plated barrel with fiberglass bullshit.
]

 

[jimduckie]

a super soaker with unlimited holy water

 

[The Austin]

Um..... A hammerburst. Because I am boring.

 

[Ulfsson]

Frickin' Power Hammer. (WH40k)

If I'm going to die, I'm going to die in style.

 

[Bob the Average]

the rocket launcher from half-life 2 get hidden fire it guide it then run and hide some where else.

 

[Slaanax]

Infinite Supply of Vortex Grenades.

 

[Scythax]

Does Skynet count?

 

[Hollock]

the BFG 9000!
and remember

Spoiler

[http://tinypic.com] "MIGHT MAKES LIGHT!" -Doomguy

 

[The_Healer]

A nail... in a plank.

Start running, seriously.

 

[Cheesepower5]

Claim Solais from Castlevania Sorrow games. B|

That or mother*EFF*ing Metal GEEEEAAAAR.

If I have to die anyway, bring me Odin. And tell him I need his spear.

 

[DownpourLiar]

At first I thought crowbar immediately, then I saw it could have unlimited ammo. So I guess I would go with some sort of an assault rifle or sub machine gun purely because I like something compact and fast shooting, I'm simple what can I say

 

[firedfns13]

A knife and a smoke grenade. Hell's minions won't be able to stop me from stabbing them since I'll be sprinting at warp factor 10.