Tertullian, Against Marcion 3.14
This interpretation of ours gains support when, in another passage, you find yourself convinced by a comparison of the remaining senses that Christ is a warrior because of certain military terms and language of that sort. David says, "Gird your sword upon your thigh" (Psalm 45:3). But what does the text say a moment later about Christ? "You are fairer than the sons of men; grace is poured upon your lips" (Psalm 45:2). I laugh at the idea that the poet would gird someone with a sword for war and then flatter him about his timely beauty and the grace of his lips. In the same way, after adding, "In your majesty ride on victoriously for the cause of truth and meekness and righteousness" (Psalm 45:4), he gives the reason: because of truth and gentleness and justice. For who would accomplish these things with a sword, and not rather the opposite—deceit and harshness and injustice—the very business of battle? Let us see, then, whether that sword is a different one, whose action is different. For the apostle John in the Apocalypse also describes a sword proceeding from the mouth of God, double-edged, razor-sharp (Revelation 1:16), which must be understood as the divine word, double-edged by the two testaments of the law and the gospel, sharp with wisdom, hostile to the devil, arming us against the spiritual enemies of wickedness and all concupiscence, even cutting us off from our dearest ones for the name of God.
Latin
Adiuuabitur haec nostra interpretatio, dum et alibi bellatorem existimans Christum ob armorum quorundam uocabula et eiusmodi uerba ex reliquorum quoque sensuum comparatione conuinceris. accingere, inquit Dauid, ensem super ++ femur. sed quid supra legis de Christo? tempestiuus decore praeter filios hominum, effusa est gratia in labiis tuis. rideo, si, quem ad bellum ense cingebat, ei de tempestiuitate decoris et labiorum gratia blandiebatur. sic item subiungens: et extende et prosperare et regna, adiecit: propter ueritatem et lenitatem et iustitiam. quis enim ense (ea) operabitur et non contraria potius, dolum et asperitatem et iniustitiam, propria scilicet negotia proeliorum? uideamus ergo, an alius sit ensis ille, cuius alius est actus. nam et apostolus Iohannes in Apocalypsi ensem describit ex ore dei prodeuntem, bis acutum, praeacutum, quem intellegi oportet sermonem diuinum, bis acutum duobus testamentis legis et euangelii, acutum sapientia, infestum diabolo, armantem nos aduersus hostes spiritales nequitiae et concupiscentiae omnis, amputantem etiam a carissimis ob dei nomen.