Jim,
Thank you for your generous praise of my modest contributions, but in truth, most of what I know of these knives comes from those two books and having seen their usage first hand during my travels in Sth America. In truth, it is very difficult to say much that is new on these knives with any certainty because what can be said has already been stated by Domenech and to a lesser extent Osornio, both sadly untranslated, and the rest is lost in the mists of time and intertwined with myths.
These knifves have gained a symbolic role in modern times, as have the Spanish navajas, both as national icons and reminder of a colorful past. As such, despite being obsolete, both have found a new lease of life. There are now superb artisans (see link), turning out pieces of previously undreamed of quality and ornateness. These masterpieces are rarely used, though it is common for well to do men to attend barbecues (Argentine Spanish: Asado) dressed in traditional garb, with a diminutive but very ornate knife tucked into their belt, but this is about as far as it goes.
And so, much of the arcane minutiae associated with these knives pertains to this modern breed. For example, according to Domenech, the Olavarria school of silver work for knives reached its full development in the 1925-40 period, an era by which the only gauchos to be found were in the theatres, not that any real gaucho could ever afford one.
From all of this, it can be seen that the indiscriminate association of these knives with gauchos is, to my mind at least, inappropriate, and a much better umbrella term is `Creole Knife' (Spanish: Cuchillo Criollo).
http://www.pallarols.com.ar/ Best seen in Spanish
Cheers
Chris