You get C***idy's revolver called "Amnesty" with the Aldocados, night before the big mission he's shooting bottles and you get to join him. If you get 12 hits he offers his gun.

you also get panam's overwatch riflle for completing The Star. i already had it (and genjiroh) so both of these rewards were duplicates for me. but thought i'd share anyway

@Talith I got to keep Genjiroh after the Arasaka ending. And no I didn't get that gun earlier in the game during the Play It Safe mission either.

SPOILER WARNING (but you're already here so):
On the Sun ending you can go back and pick up Rogue's pistol (called Pride) after Smasher kills her, and then you'll get to keep it after the ending as well, a legendary/iconic pistol with scope, muzzle, and 4 mod slots.

@talith you can if you go there outside of the mission.

If you choose to go with the arasaka option, there is an Epic/Iconic smart pistol called Genjiroh in the mansion where you rescue Hanako. But it's like the rifle you get for going with Rogue, can't keep it once you are done and go back to before the break off point.