I don't know much about their use, other than that the extreme curve in the scabbard is designed to catch the belt to allow a quick draw (most of the models I've seen don't have belt loops on the scabbard., and are designed to be tucked into a cloth belt) I always thought the curved blade of the weapon was designed to maximize its slashing capability, but apparently the curved design is an artifact of the original material of its manufacture, as before the Arabic peoples gained metal-working technology the Jambiya was made from a buffalo horn split longitudinally, then shaped and sharpened into a blade. A lot of the blades of Africa and Asia bear the design characteristics of the "Horn Age" when weapons were made from re-worked bone and horns, like the Persian and Indian Khanjar. I just learned this after I pulled Sir Richard F. Burton's "The Book of the Sword" (1884) down from the shelf today. Burton wrote:
"The modern weapon, with metal blade and ivory handle, has one side of the latter flat, betraying its origin by retaining a peculiarity no longer required. The same is the case when the whole Jumbiyah is, as often happens, made of metal." I wonder if that characteristic still shows up in modern Jambiyas?
Burton, who was an avid swordsman, doesn't discuss how it was employed. Are there systemized schools of sword and knife combat from the Arabic tribes? You would think that if there were, those techniques would show up in the knife classes taught in their armies' elite units. From the few videos I've seen of Jordanian and Egyptian special ops units training, it looks like pretty standard Applegate-Fairbairn techniques and sentry removal with a standard straight-bladed combat knife. I know there are al-Qaeda videos showing combatives training but I don't recall seeing any knife techniques being taught or demonstrated - has anyone else seen any?
It's worth noting that the 9-11 hijackers learned how to use their edged weapons at a martial arts school in the United States.