I'm not too good at modding but I do get bored and have enough knowledge of the GECK (through my experiences with the CS in Oblivion) to make small tweeks. The three weapons being offered in this mod are pretty weird and one of them has probably been done before.

The weapons:
Octo bombs: These are explosives that use bethjunkie's Octo dolls as a base, they have the exact same stats as C-4, they also appear as default C-4 before you place it (or drop it) because I was worried about obstructing the view. Also if you have problems with the octo dolls not appearing in modded interiors the octo bombs are a quick fix for that particular problem.

9mm Fat Man: I got REALLY bored and made this, it's essentially a fatman with damage and DPS of a 9mm pistol, really crap weapon use it for a bit of a laugh and then sell it, it still has the value of a fat man :P

mini nuke pistol: this has probably been done before, it's a 9mm pistol that fires mini nukes. same damage and DPS as a fat man everything else is the same as a normal 9mm pistol. This one might be a bit on the OP side, just because it's so light, easy to repair and has no skill requirements to use.

so yeah those are the weapons, they can be found in the Hunter's Farm so it's not like you'll be given access to them early on in the game.

requirements
For the octo bombs to work you will need bethjunkie's octojave mod (or at least the meshes and textures from it) I'll provide a link at the end.

installation
extract the two esp files into your data file

uninstallation
uncheck and delete the esp files.

permissions
don't upload anywhere else without my permission (not that you would want to for two of the weapons in this mod :P) and credit me (and bethjunkie and Riven) if you want to use the octo bombs.

credits
bethjunkie for her excellent octojave mod
llamaRCA for giving me the idea for the octo bombs (indirectly) through her Willow mod
The boredom ninjas for hitting me when I least expect it
Bethesda and obsidian for the game
you for downloading the mod.