[1] Likewise or similarly in other lexica. The headword is third person singular, present indicative active, of fenaki/zw (cf. pi 1419). It must be extracted from somewhere (but not from the quotation given, which contains the related noun fena/kh; cf. phi 194 and note, phi 195). Extant possibilities begin with Demosthenes (25.80 or 31.12).
[2] Theophylact Simocatta, Histories 6.5.16 (with "strength" of the trickery).