is there really such a thing as a "sterile" combat knife? I would think a little testing with an electron microscope could pretty well prove a knife was in fact a SY.
it's not an issue of being able to tell where the knife came from. It's more a matter of being able to predict where the knife will go.
Let's say that unit XYZ's area of operations is The middle east and Dan or Jerry announce that that just shipped X amount of knive to unit XYZ, then one could determine that unit XYZ is in predeployment phase.
Special operations units biggest assest is stealth. The ability to surprise one advisary is central to a lot of military doctrine. This is especially so with special operations forces.