This is a sub-page of Fallout 3 (Van Buren).
Weapons#
The Tech Demo has many unused weapons hidden in its files. Models and inventory icons for all of them exist in the game's files. There are also scripts for the weapons, suggesting that they can be used in the tech demo. However, there's no known way to summon them right now.
Of note is that it appears that Van Buren was going to have a weapon modding system, which “officially” made its debut in New Vegas.
.223 Autoloader#
A .223 pistol. It could be modded with a silencer.

.22 Autoloader#
A .22(LR?) pistol. It could be modded with a silencer.
.45 Autoloader#
A .45 pistol. It could've been modded with an extended magazine mod, a silencer, or both.


Hatchet#
A hatchet for hacking people up.
Shiv#
The useless Shiv from Fallout 2 was going to make a comeback in Fallout 3/Van Buren.
Machete#
Van Buren would've let you hack up enemies with a machete.
.45 Revolver#
A revolver chambered in .45. What advantages it would have over the .45 autoloader is unknown - perhaps none, since in many video games, including those in the Fallout series, players receive less effective versions of weapons earlier in the game.
.50 Revolver#
A frikkin' revolver chamber in .50.
9mm Autoloader mods#
The 9mm Autoloader present in the Tech Demo could've been modded with either an extended magazine, a silencer, OR BOTH!

9mm Machine Pistol mods#
The 9mm Machine Pistol that's usable in the Tech Demo could've been modified with an extended magazine and/or a silencer. There's also a listing for a “suppressor” mod, which is pretty silly, as a silencer and a suppressor are the same thing.

Sawed Off Shotgun#
The Sawed Off Shotgun is the only shotgun in the game's files.
APOLLO Laser Gun#
A nifty laser gun named APOLLO was going to be in the game. According to background info included with the design docs, APOLLO was a super-advanced laser weapon designed by Poseidon Energy that was never finished. A player with a high science skill could finish it.
(Source: http://fallout.wikia.com/wiki/APOLLO)
ARTEMIS Rail Gun#
An enormous rail gun. According to design documents, it would be an unfinished prototype weapon that a player with a high science skill could complete. It would use 15mm EC as ammo.
(Source: http://fallout.wikia.com/wiki/ARTEMIS)
Gauss Pistol#
A Gauss Pistol, which also appeared in Fallout 2. It probably used 2mm EC ammo, if the Fallout 2 Gauss Pistol is any indication.
Laser Pistol#
A Laser Pistol. Nothing special about it.
Laser Array Gun#
A large laser gun. The weapon is shaped like a Thompson SMG, which is also a shape used by the Laser RCW weapon in Fallout: New Vegas. It's possible that the Laser Array Gun evolved into the Laser RCW, as Fallout: New Vegas draws quite a bit of material from Van Buren.
Arc Welder#
Your average welding tool turned murder weapon.
Crowbar#
The Gordon Freeman special from Fallout 1 and 2 would've been used in Van Buren.
Dynamite#
The first explosive weapon in New Vegas would've appeared in Van Buren as well.
Flare#
Every RPG needs vendor trash, and a classic piece of Fallout 1 and 2 vender trash, the Flare, would've returned to fill that role just as well as in Fallout 1 and 2.
Bio Grenade#
Based on its name, it would probably be filled with some sort of nasty biological agent that would be released when it blew up.
EMP Grenade#
Based on the name, it would probably do a shitload of damage against robots. Probably a renamed Pulse Grenade, as there is no Pulse Grenade listed in the game's files.
Frag Grenade#
The classic explosive grenade would've returned in Van Buren.
Plasma Grenade#
The Plasma Grenade would've returned in Van Buren.
Hand Flamer#
This would be a mini version of a Flamer. It looks a lot like a spray can.
Heavy Wrench#
It seems that Van Buren would've let you go Engineer on your foes.
Kitchen Knife#
A kitchen knife. Simple, yet deadly.
Laser Saw#
The inventory icon shows a red laser between the top and bottom cylinders on the top part of the weapon, which isn't on the actual model.
Lead Pipe#
A...lead pipe you would beat people over the head with. This reappeared in both Fallout 3 and Fallout: New Vegas.
Night Stick#
Another generic melee weapon.
Rocks#
Just in case you were worried, Van Buren would've had worthless weapons, such as a throwable rock.
Switchblade#
Yet another bladed weapon.
Table Leg#
You would've been able to beat enemies to death with a damn TABLE LEG. Hardcore!
Throwing Knife#
One of two non-explosive throwable weapon in the tech demo's files.