adversary
From LSJ
ὅπλον μέγιστόν ἐστιν ἡ ἀρετή βροτοῖς → man's greatest weapon is virtue, virtue is the greatest weapon for mortals
P. and V. ἀνταγωνιστής, ὁ, V. παλαιστής, ὁ, ἀντηρέτης, ὁ, ἐνστάτης, ὁ, or use adj., P. and V. ἐναντίος, P. ὑπεναντίος; see opponent, enemy.