Γερήνιος ἱππότα Νέστωρ
See Frame 2009 for an in-depth exploration of the epic tradition about Nestor and how it is encapsulated in the phrase hippota Nestor. That Frame could write a work of nearly 800 pages on the implications of this phrase in the epic tradition reveals just how much meaning can be encapsulated in a single epithet. (See also above on 10.3.) Of gerēnios Frame writes (2009:600n189):
In his separate epic traditions Nestor was a young man; only when Nestor was added to the saga of Troy was the figure of the old man created (cf. Cantieni 1942:87). The idea that at Troy Nestor operates among the third generation of heroes during his own lifetime is meant, I think, to establish a sharp divide between the aged Nestor (who is new) and the young Nestor (who is old); a middle-aged Nestor does not exist in epic as far as we know. It was perhaps to distinguish the old hero at Troy from the young hero in Pylos that the hippóta Néstōr of ancient Pylian fame became Gerḗnios hippóta Néstōr at Troy, if Gerḗnios, derived from géras, “privilege of the old,” simply means “old,” as forcefully argued by Bader 1980:55–56: note in particular Iliad 4.325, where Nestor, referring to his role as counselor and speaker (i.e. to his Homeric role in essence) says τὸ γὰρ γέρας ἐστὶ γερόντων, “for that is the privilege of the old”; a full and convincing morphological analysis of the derivation of Gerḗnios from géras has now been offered by Timothy Barnes in an unpublished paper delivered at the 2008 annual meeting of the American Philological Association.
The theory that gerēnios relates to the privileges of old age is strengthened by a notice in the Townley scholia to Iliad 16.196 that “some” have Γερήνιος ἱππότα Φοίνιξ in place of γέρων ἱππηλάτα Φοίνιξ. (Otherwise, the phrase is used exclusively of Nestor.)