The top jaw of the cock is missing, but otherwise it appears to be in decent shape. IMHO, it was intended as a weapon, as opposed to a souvenir "gun" or a recently made novelty of some kind.
Those combination guns were considered novelties at the time they were made, and were not popular, which is why they are rare. They were expensive, but the main reason they were not used was that that the pistol weight made the sword unwieldly as a sword, and the blade made the pistol unwieldly as a pistol. It was easier to carry a sword in a scabbard and a pistol or two in a sash or holsters.
It looks European and if so there should be some proof marks on the gun even if there is no maker's name.
Value? Anybody's guess is as good as mine. With no identification and no historical association, I would say maybe two or three thousand (assuming it is actually old). If it can be connected with an historical personage or activity, or a well-known maker, the price could go very high.
Jim