Bu then I though, no, don't dismiss his missive. The guy saw what he saw. So I did a thorough search, checked with sources, pored through the extensive stock of catalogs I keep under the mattress, and consulted with the world's leading experts on multi-tools. And my conclusion: You were hallucinating. If there is such a thing, and I doubt that there is, it is SO obscure as to defy even my vast gear-finding abilities. I mean, in a way it doesn't even make any sense. The abuse you'd put the watch through by using it as a hardware tool would test any shockproof timekeeping device. And to be useful, a signal mirror has to be 2X4" or so, otherwise what's the point? If it does exist, I'm sure it hangs from a lanyard-it sure wouldn't fit in a pocket.
My advice: Put the wristwatch/stopwatch on your wrist, a Leatherman in your pocket, and a compass and signal mirror in your pack.