Maybe it's the robe of a court wizard, provided by the royal court, and since he was fired (although he didn't realise it at the time), the robe was taken away since he's no longer a court wizard. Though I doubt that, despite saying it myself.
Suspiciously much like a doormat, goody two-shoes MC. I guess I'll give this a couple of chapters to see if he develops any sense of self-confidence.