Ah yes, well as much as Renaissance can be perceived as a cultural flow, though. Because by the time the 100-year war ended, all parties involved could not believe that, albeit they distanced themselves from the Middle Ages and made some scientific advances, the worst war in history had just ended (but waged for a long while under their watch).
About how nobles behave: there are some specific books from the Middle Ages that exactly describe the life of the "exemplar" nobility.
They could blame a lot of that on the mercaneries though, since many of the garrisons the English left behind in places were in fact mercaneries who decided... wait, the entire campaign of the Black Prince (who in England is thought of fondly, much like the way that "The Black Watch" is one of the most famous British/Highland brigades - a great-uncle of mine in 1936 left his hometown and travelled all the way up to the Highlands to join) was about pillaging the south of France until there was nothing left. His entire army was full of mercaneries, so my point sorta stands up except that they were acting under his orders. They did their own pillaging later on as well.
That said it was the worst war that the French and English had fought, not the worst in all history to that stage.
Anyway, back on topic. The noble "guides" of the Renaissance (like Baldassarre Castiglione's "The Courtier", which was turned by the English from a novel into step-by-step How To Guide) are influenced by the knightly culture instilled by the 12th century troubadours. A perfect example of the archetypal medieval knight however would be Sir William Marshal. On the one hand he was full of all the qualities of knights that were most admired, and even told his squire upon his deathbed that the three qualities a knight must have are Wisdom (to give ones liege good counsel), Fidelity (to your liege) and Valour (the ability to kick ass and take names). He then had a singing lesson with his daughters. On the other hand he also owned a torture chamber and frequented it regularly.