It's from an anonymous seventh-century epitome of ecclesiastical histories. Another manuscript left a blank space for this word, suggesting to me that the scribe didn't know what to make of it either. My best guess, if it's not a hopeless scribal blunder, is some form of ἀπόφημι, maybe a legal term qualifying συνηγόρων (or maybe it should be read as all one word, ἀποφησκοσυνηγόρων). Any thoughts at all?