The Mystery Knife

If you can help explain the origins of this knife, I'd be interested in what you might know about it.

About 30 years ago, it was purchased in an antique shop in Paris. The shop owner at the time said it was an "Italian medieval dagger." Much more recently, my father and I took it to the Antiques Roadshow when it was in Seattle. (Interesting experience and nowhere near as enjoyable as it looks on TV....) The guy who looked at it was entirely dismissive of that history and said it was much more recent, that the sheath was even younger, and -- seeming grumpy and tired -- he basically wanted us to move right along.

My own research after that didn't match either story, the one from the shop that sold it or the guy who appraised it for the Antiques Roadshow. Similar ones I've found online have had a sheath similar to the one shown here, so I'm not even sure the bit about the sheath being younger is accurate.

My best guess is that it's a Spanish naval dirk from the 19th Century.

I found one with similar design in poor condition and no sheath with an estimated value of around $100 (USD). Another one that was similar, had a similar sheath, did not have the blade detail shown in my photo, and was in fair condition had a price tag of $295. The latter was referred to as a "19th Century Mediterranean Dagger."