Night Ninja said:
Heh, the blade is a shamshir. I should learn to check the source before posting.
http://en.wikipedia.org/wiki/Shamshir
Yes, it's a shamshir. You can tell (if anyone cares) because it has the curved pommel and the edge is greater than uh...I think it's 18 degrees (I only had to care for one semester, sue me). Although scimitar is not technically incorrect, since it's now a catch-all for Turkic-Arab sabres.
It's a very, very nasty weapon employed to great effect by Arab cavalry when they kicked the Crusaders out of the Holy Land. It's been around since Alexander's time, however, and has probably been employed to great effect by Arab cavalry pretty much forever.
It's not a very effective weapon dismounted, however, which is why you see weapons like the scimitar and kilij, which can be used for the normal thrust, slash, parry of dismounted combat.
As far as the katana goes: it's very difficult to use one mounted (they have a tendency to get caught and drag, which when mounted will pull the weapon free of your hand), which is why the samurai's weapon of choice was (wait for it) the daikyu (great bow). Mounted samurai who found themselves without a daikyu would often rely on a spear.
Incidentally, cavalry weapons aren't traditionally single-edged for no reason. A single-edged blade is favored by cavalry for one simple reason: momentum. What happens when your two-edged sword gets swung back against your horse by the force of the blow? Laming your own horse is poor form. The curved blade is similarly functional, allowing the rider to more easily pull the blade free of the body.
Katanas don't benefit from that aspect of design, though, since they're cutting blades and not chopping blades (which rely more on impact than a slicing motion). They naturally want to bite in on its edge, whereas a sabre wants to pull free on its edge.
Personally, however, I'd like to see the real Scottish backsword, even if they were more an evolution of the 17th century and on forward.