The headword is the aorist active participle, masculine nominative singular, of the compound verb e)pife/rw. (For this sense of it see generally LSJ s.v., I.3.) It is perhaps extracted from the quotation given here, though there are numerous extant alternatives.
[1] Adler labels this an intrusive gloss and cites the Lexicon syntacticum of Codex Laurentianus 59.16 as a comparandum.
[2] Procopius, History of the Wars of Justinian 7.15.15 (web address 1), during his siege of Rome in late 545 CE, Totila (cf. tau 879) interrogates and punishes a bishop named Valentinus; cf. Kaldellis (411).