γνωστήρ
From LSJ
πάντες γὰρ οἱ λαβόντες μάχαιραν ἐν μαχαίρῃ ἀπολοῦνται → all they that take the sword shall perish with the sword
English (LSJ)
ῆρος, ὁ,
A one that knows: surety, X.Cyr.6.2.39, BGU 1032.11: witness to identity, POxy.496.16 (ii A. D.). 2 inspector, PAmh.2.139.23 (iv A. D.), PLond.3.1249.3 (iv A. D.).
German (Pape)
[Seite 499] ῆρος, ὁ, Bürge, Zeuge für eine ihm bekannte Wahrheit, καὶ ἐγγυητής Xen. Cyr. 6, 2, 39.
Greek (Liddell-Scott)
γνωστήρ: ῆρος, ὁ, ὁ γνωρίζων, ἐγγυητής, Λατ. cognitor, notor, Ξεν. Κύρ. 6. 2, 39, πρβλ. Piers. Μοῖριν 116