Fallout 3 weapons

Pistols

 * Unique weapons are highlighted with a darker background.
 * Pistols are affected by Gunslinger.
 * ¹ Weapon is silenced.
 * ² Weapon is scoped.

Rifles

 * Unique weapons are highlighted with a darker background.
 * Rifles are affected by Commando.
 * ¹ Weapon is silenced.
 * ² Weapon is scoped.

Shotguns

 * Unique weapons are highlighted with a darker background.
 * Sawed-off shotguns are affected by Gunslinger.
 * All other shotguns are affected by Commando.

Submachine guns

 * Unique weapons are highlighted with a darker background.
 * SMGs are affected by Gunslinger.

Direct-Fire

 * Unique weapons are highlighted with a darker background.

Area-of-Effect

 * Unique weapons are highlighted with a darker background.
 * Area-of-Effect weapons have a Crit % Modifier of 0, which eliminates any chance to critically hit with them.

Energy Pistols

 * Unique weapons are highlighted with a darker background.

Energy Rifles

 * Unique weapons are highlighted with a darker background.

Bladed

 * Unique weapons are highlighted with a darker background.
 * Melee damage is doubled in V.A.T.S.

Blunt

 * Unique weapons are highlighted with a darker background.
 * Melee damage is doubled in V.A.T.S.

Unarmed

 * Unique weapons are highlighted with a darker background.
 * Unarmed damage is doubled in V.A.T.S.

Custom-built weapons

 * Red codes are for the Schematics.
 * Cryolator, also a custom-built weapon, was cut from the game

Cut Content
Cut content, these weapons are only available through console commands.

Cut content weapons that are only obtained through glitches OR console commands.

Concept Art Weapons
These weapons were made into concept art but never made into the base Fallout 3:
 * Cryolator
 * Mason jar mine
 * Piggy bank grenade
 * Air hammer gun