OK; long post coming up...
"Chrome vanadium" steel; - vanadium is used in steel alloys to retard the growth of the grain and control grain structures during heat treatment; alloys containing vanadium withstand shock better than regular carbon steel. Chrome increases depth of hardening and responsiveness to heat treatment. Both additives have a downside - chrome promoted cracking during the forging process, vanadium promotes 'red-hardness' ie resistance to the hammer at red heat.
Chrome and vanadium are present in L6, used for making saw-blades (o.o3% chrome, 0.15% vanadium) and the stainless air-hardening alloy D2 (12% chrome, 1% vanadium).
I believe Del Tin do use chrome vanadium alloys for their blades; this would make sense, since their swords are extensively used for edge-to-edge bashing in re-enactment 'fighting', where the toughness imparted by vanadium would be invaluable. The drawbacks during forging of both chrome and vanadium don't apply to Del Tin blades, since they're not forged but ground down out of laser-cut blanks and then heat-treated. If Windlass (makers of the most commonly available 'falcata' replica)purport to offer chrome vanadium alloy blades, I personally wouldn't give spit for them - WC blades *are* forged, I understand, and the drawbacks implicit in the materials would only amplify their general lack of reliable quality.
Del Tin used to make a 'falcata' replica (don't know if they still do) - given the *very* high reputation of DT products and my own experience with DT swords, I guess you couldn't go far wrong with one, tho' they're quite expensive IIRC
As for the machaera, aka kopis, aka falcata, I've posted more than enough about the history of this blade since I started hanging out in the cantina, and I won't bore everyone again.
The first khukuri I ordered from HI was a special-order replica of a machaera, based on sketches I sent to Uncle Bill. When it arrived, the blade was outstanding in both quality and aesthetics (wonderful deep-fullered blade and carved handles) and bore virtually no resemblance whatsoever to either my sketches or an ancient Greek sword (but it's a masterpiece of the kamis' art, so who gives a damn?)
A very talented British swordsmith called Ian Whitefield made me a superb replica machaera, including the integral hilt horns. From using this, I can testify that the machaera is a wonderfully efficient cutting tool, similar to a khuk but with significant differences; I'm not qualified to pontificate about martial arts, but IMHO a good machaera replica would make a better fighting weapon than any khuk except, possibly, an oversize and elongated Gelbu Special.
I'm sure that Bura or Kumar could make a really first-class machaera, if they had a wooden pattern to copy; as Bill's told us scores of times, the kamis have trouble working from a sketch or drawing. If the copy included the integral hilt horns of the ancient Greek original sword (now in the British Museum, London) that Museum Replicas and Fulvio Del Tin copied, pretty much exactly, when designing their 'Spanish falcata', it'd be an expensive piece to make - forging the horns took Ian Whitefield longer than making the blade. But the horns aren't an essential part of the design - most machaeras had a simple cross-hilt - and without them, the machaera is no harder to make than a fullered khukuri.
If five people want one, I'll gladly make a wooden model.
) were using kopi(sp?) instead of the standard straight blades you kind of expect to see. Now I always told myself that the next blade I buy from HI would be more suited to battle, and I was hoping to find a blade similar in form and function to the kopi that I saw. 
