Location: Black Mountain
You will need to kill the Nightkin Sniper that is at the very top of Black Mountain. Then head to where his body is and you will find that he is carrying the Annabelle Missle Launcher.
One of the companions, Raul Tejada, will also be found inside of the Prison Building here at the top.
Location: Nellis Array
This weapon will be found lying on the floor near the Ant Mount in Nellis Array.
Location: Quarry Junction
Another Location: In the mountains south of Jacobstown
There are a few locations for the Fat Man unlike any of the other unique weapons; this is still counted as one though. It will be on the edge of the southern green pond inside of Quarry Junction. Next to it will be a skeleton, both of which are partially in the water. It would be much easier to have the Side Quest “Bleed Me Dry” found and active when you enter the Quarry so that you can collect the Deathclaw Eggs while you kill them in this area, unless you have already completed it.
Another location you can find another Fat Man is in the mountains south of Jacobstown. This can be found during the same Side Quest “Bleed Me Dry” but earlier when you are collecting the Cazador Eggs. It will be on already dead Super Mutant Master lying on the ground to the left.
Location: Camp Searchlight
Requirements: You must start the game with the Wild Wastleland Trait, otherwise you will not be able to get the Holy Frag Grenade.
This grenade will be in the basement of the eastern church in Camp Searchlight as long as you meet the requirements above.
Location: Dead Wind Cavern
This weapon will be on the floor of the cavern near the body of a dead Brotherhood of Steel Paladin in Dead Wind Cavern.
Tags: Fallout: New Vegas