Alright, I'm gonna cut to the chase on this.
Although we have a vast amount of weaponry available to those of us that like to live life on the edge (See: Everything is a melee weapon, even your studdly if you're brave enough.) There is one pretty neat (Slightly outdated) and potentially CPAF weapon type I'd love to see added.
Bows. More specifically, a Compound bow/crossbow with mods similar to that of the firearm modification kits. Obviously, these wouldn't really fall into the current weapon skills, so that might be added. But hell, how badass would it be to go out into the badlands with a crew, roll up in your buggy and spear a god damn dune dragon through the skull with a freaking crossbow bolt.
That is one suggestion, part two is more for flavor and does fall under weapon mods.
Paint jobs. I know we have engraving and such already, for those of you (or us) that like to have flashy little signatures on their gat as they pop another couple rounds into this week's mix trash, but how much cooler would it be for say, said mix trash to be gatted by someone who took the time and effort to paint their gun a nice snazzy orange. Or by a joy who decided she wants that little sebby in her pocket to be a bright neon pink, because nothing is more shit hot scary than being pop-popped in the chest by a whore with a hot pink pistol.
The paints are entirely thematic, I can see Mixers using their gang colors on their machete blades, guns, whatever they used as a weapon. It's been done a fair few times, especially in games that meet the theme (See: Brink. Decent game, fairly CP, had this kinda feature.)
Anyway, just a thought.