PHEBUSEO is the name of the Trojan hero who fights to save Antenor from capture by the Greeks, Tr IV.50-54. He is not mentioned in Boccaccio's Il Filostrato, and Chaucer apparently invented the name.
Phebuseo, with stress on the penultimate syllable, is derived from Phebus, which it so much resembles, and occurs in final rhyming position, Tr IV.54.