I have a book ("Firearms Curiosa") which I have misplaced, but in it is a chapter on a combination blackpowder pistol and 8"ish cutlass. Pretty odd, you say. Well, this particular thingy was issued to the US Navy in moderate numbers. Yikes. Wonder why that didn't take off?
http://www.gunsamerica.com/guns/976101085.htm
http://www.gunsamerica.com/guns/976101085.htm