[Nihl]

Thanks for the positive responses both of you! What I wrote is mostly the result of me pouring over and analyzing every detail of every single example of a congavellum I could find on the net. Indeed, these things are quite rare, but they tend to pop up with a strange regularity when you know what to look for.

In response to Jim

I have never heard the term 'congavellum'!

"Congavellum" is generally one of the terms that pop up when one looks into what exactly "malabar choppers" actually are. Given that some people are probably curious what those other terms are (including Jim I'm sure ), here's my best attempt at defining each of them:
Aruval - The tamil term for a type of long billhook machete. Whether or not this term could be applied to a historical form of sword remains to be seen, as no examples of true antique aruvals (that is to say billhook-esque swords originating from tamil nadu) exist to my knowledge.
Kathir Aruval - The clear agricultural version of an aruval, taking the form of a slightly-more-elaborate-than-usual sickle, but otherwise intended more as a ceremonial implement than a weapon.
Koduval - The Malayali term for a machete, koduval appears to apply exclusively to machete tools, rather than machete-swords, so it is a red herring here. Possibly, the term could be applied to the swords used by the mappila people, given how close they look to modern koduval machetes, but this remains to be determined. Linguistically it might be distantly related to congavellum.
Kongavela - Seemingly used interchangeably with congavellum, it's possibly a kind of intermediary between congavellum and the previous term koduval. Possibly could be used to refer to the 18th century variety of congavellum that are more sickle-like and less sword-like.
Matchu/Machchu - Karnataka's distinct take on the "chopper" design, the term "Matchu" as collectors use it applies to all malabar choppers with long handles and short blades - in essence the southern parallel to the northern Bhuj knife-axe. Worth noting that in Kannada "Machchu" just means "machete", so in terms of historical accuracy any chopper that found its way into karnatakan lands would have been called a matchu.
Veecharuval - The long, two-handed version of an aruval (veech indeed translates to something like "long" or "big" in tamil). Interestingly, in contrast to the absence of extant antique aruval, quite a few of these large, two-handed, billhook-like swords from tamil nadu still exist. Although it's possible they were used as large agricultural tools, based on the forms of extant veecharuval it seems likely they were more used for ritual executions and - before that - possibly in combat as well.
And of course there is also
Congavellum - A kind of forwards curving sword used by the Nayar warrior-kings in the late medieval-early modern period of malabari history. After being deposed by the Travancore kingdom, the nayars adopted their own kind of tulwar-style val (the Kayamkulam Val as collectors know it (val being the generic word for sword in malayali)), while continuing to make congavellum, but likely using them mostly for ceremonial purposes instead of martial ones.

I'll try to attach pictures to correspond with each of these words, however some don't line up with anything, and others are easier to find as modern tools than as antiques. This also doesn't include congavellum of course as I already showed them in my last post.

In response to Drac2k

more amazing was the fact that you had 3 of them!

I actually have 5! This is mostly the result of circumstance, however, rather than me having magical congavellum-acquiring powers. The three that I have previously shared a photograph of all came from the collection of Roy Elvis, a south indian arms researcher who actually inspired me to look into these weapons in the first place. I bought them from him after he allegedly acquired them from a dealer in kerala, who got them directly out of an old "forgotten" armory in northern kerala. The fourth one I have comes from our own RSWORD on the forum, and only the fifth one I was able to find "out in the wild" at an auction house. Still impressive I suppose nonetheless, but I just want to make it clear my collection of them is from pure luck rather than years of deliberate, arduous looking.

I looked up a few references on Nayar, Nair History and found them to be fascinating.

Indeed the nayar are quite cool! From what I've personally read, they were in effect the southern equivalent of the Rajputs of northern india, and led feudal kingdoms all up and down the malabari coast until being overthrown by the travancore kingdom. After this they became more or less aristocrats under the new kingdom, despite otherwise being dethroned and stripped of their rank. Nayars continued being "warrior people" up until colonial times, and made up some of the native forces that the british allied with to help depose Tipu Sultan.