Gamers like weapons, and gamers like mashups. It's surprising, therefore, that you don't see a lot of combination weapons in RPGs or wargames. I think it may be because most fantasy games take their inspiration from medieval settings and combination weapons, which include both a hand-to-hand weapon of some kind and a firearm, are really a Renaissance phenomenon.

Let me show you the kind of thing I'm talking about. These two examples are from Poland, where pistol/axes seem to have survived particularly late as cavalry weapons. I guess the idea is that you do that one-shot charge thing that 17th-century cavalry were so fond of, then shift your grip down to the handle of the axe and start busting heads. The first one in particular seems like a pretty robust piece.

I think it wouldn't be hard to get gamers hyped for this type of thing -- in particular, I can see it as something that you'd see in WHFRP, either as just a particular local specialty or as the kooky invention of some weirdo. Of course, mechanically in WHFRP (2nd ed, anyway) hand weapons aren't distinguished, so there's not much point. Still ...

 Anyway, most combination weapons, as far as I can tell, are not like this. They're more like wealthy people's playthings. Take a look at this example from the Tower of London.

This is an example of a charmingly brutal Renaissance polearm called a "holy water sprinkler," and for added comedy value it's got three pistols built into it, the idea being, I guess, that if you really don't like somebody you can shoot 'em three times, stab them with the pointy bit, and then bash them round the head with the mace part. It's known as "Henry VIII's walking-staff," which is pretty good. But somehow it seems kind of impractical, or at least impractically expensive. It's not clear what advantages it really has over a plain head-beating club and a couple of pistols. 

I do like the idea of weapons designed along these principles -- or, heck, not even weapons, anything. An old D&D joke is "a wizard did it," but I think "a rich idiot did it" is equally plausible. I know my players have recently spent a lot of time looting the homes of rich idiots, and I do sort of like the idea of giving them some comically implausible weapon that's so valuable they can't pass it up but so distinctive they can hardly fence it: "oh yeah, it's a halberd, but it's got, like, a crossbow built into it and then when you push this button knives pop out...". 

Likewise, I can legitimately see characters wanting one of these gun-shield things. People used to think these were just another armourer's fancy, but there is some new thinking that suggests they were actually used -- the examples in the V&A, for instance, have some powder burns and stuff, so they must have at least been test-fired. 

Some of them were probably intended for naval use, the idea being that you run up to the gunwale, slot the shield over it, and bang away, which I guess is fair enough. Others were probably for hand use, which is less practical-seeming. Might have been hard to aim. I can definitely see this in the hands of a WHFRP character. 

If you look at the modern version of this, of course, you can see the problem -- once you have relatively modern technology, there's not much point in having a gun-shield rather than a gun and a shield if you happen to want it. But more broadly, I think these combination weapons are actually really well-suited for gaming because they have all the problems that games typically don't account for -- clumsy, unwieldy, a pain in the ass to carry everywhere, and expensive. 

I suppose if you're really committed to the idea of emphasising the clumsiness and so on, you could do it Paranoia-style, and have the PCs be issued a bunch of clumsy, malfunctioning combo-weapons by some head-in-the-clouds R&D jagoff. "Hey guys, we've attached a chainsaw to this plasma generator. Now you have a mixture of close-combat utility and ranged firepower."

Obviously, that isn't a joke in all games.