This rumpled knight is every absent-minded teacher you've ever had all rolled into one fuzzy little ball. He teaches history to the pages and becomes something of a mentor to Alanna. She first meets him in the classroom: "He was short and plump, with long brown hair streaked with gray, and a long shaggy beard…He was the oddest mixture of disarray and good nature" (2.107). Given this description, we imagine that it's been a while since Sir Myles has revisited his warrior training.
Myles is also characterized as "the Court drunk" (2.122), and over the course of the story, we see him drinking at most social functions. Maybe he just really likes the taste of brandy … or maybe he truly has reason to feel disenchanted with life at court. He explains to Alanna bitterly, when he's struggling with Ralon bullying her: "I truly love our Code of Chivalry. We are taught that noblemen must take everything and saw nothing. Noblemen must stand alone. Well, we're men, and men aren't born to stand alone" (3.60). Ouch—sounds like this guy has had some serious grief in the past.
However, Myles is a big supporter of "Alan." When Alanna asks for Myles's help in clearing out Jonathan's sickroom during his bout with the Sweating Fever, Myles gives Alanna the chance she needs to save Jonathan's life. Further, Myles brings Alanna to his estate at Olau, in part to give her the chance to see more of Tortall. But Myles also had a recurring dream about that visit, leading him to say: "When the gods brush my life—they brush everyone's life at some point—I get nervous" (6.143).
What does this tell us? He's a pretty astute guy with a clear eye for human nature, and it reinforces our feeling that Alanna is off to a good start. For all that Sir Myles claims to be a simple man, the fact that he supports Alanna so wholeheartedly makes him pretty special.