Perhaps graeculus, often translated as Greekling?
It refers to Greeks who held positions of some import in Roman society due to their education and higher learning yet were considered too Greek to actually be considered proper Romans and, therefore, part of Roman society. It was also used to mock those Romans who exhibited a taste for Greek language, learning and customs, most (in)famously, of Hadrian in the Historia Augusta but also of Claudius in the Apocolocyntosis (see section 5).
The diminutive suggests a pejorative, as does its use in context (for example, the graeculus esuriens in Juvenal, Satires, 3.78 or almost anytime Cicero uses it!). The animosity inherent in the term seems to lie in the resentment of the erudition and cleverness of the Greek. This is perplexing as Greek literacy was considered cultured and elegant among Roman elite. Indeed, Cicero seems to use graeculus to mock Verres’ lack of authentic Greek learning (Against Verres, speech 2, book IV.127 – quite funny in its scathing sarcasm so I include a link: Against Verres). It has also been debated whether the use of graeculus to label Hadrian was a compliment or an insult.
Nevertheless, I don’t know if someone would lay claim to the label graeculus as a matter of pride. Perhaps for a successful, well-educated Greek in Rome, appropriating the term ironically as a marker of his Greekness could be an act of self-affirmation. Macrobius (who was possibly Greek himself) seems to use graeculus in an almost affectionate way. See the Saturnalia VI.26, for instance, when a guest exclaims “εὖγε, graeculus noster!/Well done, our little Greek!” after a very erudite exposition of the nervous system without any apparent malice, and also at II.31.
Thus, graeculus could perhaps encapsulate the idea of someone with great erudition and skill but on the outskirts of society. Further, its use as a pejorative or a compliment seems to lie in the eyes of the beholder (so to speak). Of course, it is also a racial epithet so perhaps not quite what you’re after. Even so, I thought it an interesting possibility so persevered with the research!