I am not particularly familiar with Stephen Maturin, other than his appearance in Master and Commander, Far Side of the World, in which he does not fight any duels as far as I can recall. I am also unclear on exactly what a "spring quillon" is, although I can surmise it is some sort of guard extension that pops out to facilitate binding and disarming the opposing blade. So, bearing in mind that I am speaking from a position of ignorance on these matters, let's talk about what I do know.
First of all, spring-loaded trick weapons were not common, and certainly not in the early 19th Century. In the early 1800s, quillons were a largely obsolete feature of swords, and were only preserved as a decorative affectation. That meant they were small and stubby, if they existed at all, and nearly completely hidden behind a shell or dish guard on the duelling swords of the time. Fencing techniques of the era did not make use of quillons for defensive purposes, and it is questionable how useful they would be if deployed by surprise. I mean, if they were useful, why did they disappear? They had some utility against cuts, but in that respect they had been supplanted centuries earlier by basket-style hilts, which by the early 19th Century had evolved into the stirrup and neoclassical sabre guard.
Now, spring-loaded trick weapons were a thing in some times and places, so it's not a complete fantasy, merely anachronistic. Spring-loaded triple daggers were a thing in the early 1600s, for instance. Not exactly common, but the sort of novelty that could be purchased if you had the money to blow on that sort of thing. I would file them in the same category as sword-guns: clever gadgets that were aimed at collectors and enthusiasts for that sort of thing. In the linked case, the spring-loaded blade was intended to be useful for enhanced parrying and blade-catching performance, so perhaps that's what the author had in mind. But if so, he's about 200 years off what would have been considered appropriate for the time. The early 1600s were the "wild west" era of dueling, when there was a lot of fluidity about what constituted fair and appropriate practice, which was further confused by the probability of random street fights with swords.
But the early 1800s was a very different time. Street fighting with swords was much less likely, and a duel with swords would have been governed by conventions and the oversight of seconds, such that trick weapons would be highly discouraged and quite likely to have a devastating impact on one's reputation if one attempted to make illicit use of them in an affair of honour. And since the whole point of a duel of honour was to save one's reputation, it would be quite contrary to the purpose of the encounter.
For more insight into the notion of dirty tricks in dueling, check out these other threads on the subject:
