Also, how technical was the training prior to gunpowder? I mean, was the learning curve years or more like, here's your sword, swing hard and often until you are dismembered ?
While you are waiting on an answer try this thread: from /u/bluestraggler:
I can't say much about peasant armies or levies and the like, but professional soldiers would have taken their sword training extremely seriously. One of the ways we know that is that there were dozens of "fight books" or fechtbucher that were left behind by sword masters, which detail, either in poetry or through illustrated plates and glosses, various plays, devices, and tricks that you could use in a sword fight.
The first European fechtbuch we have, the MS I.33 (or the Walpurgis Fechtbuch), dates from 1320, and describes combat with the arming sword and buckler.
As with all other fechtbucher, the plays runs from simple to extremely complex, and it takes serious study to unpack some of the elements required in certain plays. The modern Historical European Martial Arts community is attempting to recreate many of these manuals as close to the original intent as possible (obviously without killing anyone).
After I.33, most of the manuals and treatises we have concern the longsword, or bastard sword. A two-handed double-edged sword with a blade ranging in length from 1m to 1.2m. The earliest treatise/fechtbuch available on the longsword is from a man named Johannes Liechtenauer (he may be an apocryphal figure, we know next to nothing about his life) who:
"learnt and mastered the Art in a thorough and rightful way, but he did not invent and put together this Art (as was just stated). Instead, he traveled and searched many countries with the will of learning and mastering this rightful and true Art."
Liechtenauer later wrote the zettel (the "recital" as it's sometimes translated) which is a poetic/mnemonic account of principles of masterful fencing. Based on the rather advanced concepts and complicated devices contained in the zettel (and further extrapolated in later treatises, which gloss, expand, and illustrate the zettel), it was likely that there was some sort of commonly-understand or instinctual method of fencing called "common" or gemeynfechten on which Liechtenauer's principles are based.
Liechtenauer presents "master" or "secret" cuts, called "meisterhau" that are intended to work against common fencers by using their predictable techniques against them. Many of the techniques are used as defenses against a cut from above from your opponent's right side, sometimes called a "peasant stroke" or a "buffalo cut", as it was believed to be unlearned, instinctual, and over-powered. A student of Liechtenauer was supposed to be able to effectively deal with a common fencer by utilizing these "secret" techniques.
The vast number of masters that we know about (most of what we know is helpfully compiled in the wiktenauer website, which is a wonderful resource for medieval/early modern/renaissance fencing) implies that these "secret" techniques weren't so secret. In fact, masters were grouped together by their affiliation with the Art in the so-called "society of Liechtenauer" which spread out all around central Europe in the 15th century. Later groups, like the Marxbruder, were associated strongly with landsknecht mercenaries, who almost certainly trained in Liechtenauer's principles. "Masters of the long sword" in landsknecht companies were apparently entitled to significantly higher pay, which made training with the sword a high priority.
Later, in the 16th century, the printing press made the mass publication of manuals available far more easily than before, and with the expansion of the burgher class, the popularity of fencing rose significantly. Fencing masters like Paulus Hector Mair and Joachim Meyer not only published treatises instructing students on fencing with the longsword, but many, many other weapons, and often held public fechtschulen or fencing festivals, in which fencers would demonstrate their skill and bravery in tournaments. The tournaments were non-lethal and fought "to the bloom" meaning that to win, you had to make your opponent bleed. They had their own rulesets and common practices, making longsword - and dusack, rappier, dagger and wrestling - fencing very similar, in some ways, to modern fencing.
You might be interested in an earlier post of mine that expands on the role of Meyer and Mair here.
None of this is to say that training under a master associated with Liechtenauer was common, but it was certainly possible that these teachings were quite available, and that professional soldiers would make it a point to seek out fencing masters or experienced soldiers to teach them the very difficult aspects of fencing that would keep them alive on the battlefield. Of course, with the rise of gunpowder and the pike and shot era, fencing with swords on the battlefield was becoming less and less common, though the sword's importance as a status symbol, a means of displaying skill and bravery outside of battle was, by the mid-16th century, very common and quite important.
I always recommend the Wiktenauer wiki, which is a wealth of information lovingly compiled by HEMA scholars and is completely free to anyone. Most of the information in this post comes from wiktenauer, which is based almost entirely on primary source material that has been digitized.
For contextual information on Meyer, The Art of Combat and The Art of Sword Combat which are translations of two of Joachim Meyer's treatises by Jeffrey Forgeng, have biographical information in the forewords.
And lastly, The Martial Ethic of Early Modern Germany is a fabulous book that covers the social aspects of armed service, duelling, and other violent aspects of 16th century German life. it's expensive and hard to come by, but I highly recommend it.