Augustine of Hippo

"The wicked have drawn out the sword, and have bent their bow, to cast down the poor and needy, and to slay such as be of upright heart" (ver. 14). "Their weapon shall enter into their own heart" (ver. 15). It is an easy thing for his weapon, that is, his sword, to reach thy body, even as the sword of the persecutors reached the body of the Martyrs, but when the body had been smitten, "the heart" remained unhurt; but his heart who "drew out the sword against" the body of the just did not clearly remain unhurt. …

Exposition on Psalm 37 ↗

Ambrose of Milan

Moreover, he adds: Behold, they have unsheathed the sword, sinners have bent their bow, to cast down the needy and the destitute. What is the sword of the sinner, if not the opposite of the sword of the Holy Spirit? Scripture has taught me this sword; the Apostle taught it, saying that we have the breastplate of righteousness, and the shield of faith, and the helmet of salvation, and the sword of the Spirit, which is the word of God (Ephesians 6:14 et seq.). Therefore, the word of God is the sword of the Holy Spirit. …

Commentaries on the Twelve Davidic Psalms ↗

Thomas Aquinas

Next, when he says, "The sword," he adds about the outward effort of the wicked; and regarding this he does three things. First, he shows their effort. Second, their intended goal, at "To deceive." Third, the outcome of this effort, at "Their sword." Regarding the first, he does two things, inasmuch as their effort against the good is twofold. First, he shows their effort through open persecution. …

Exposition on the Psalms of David ↗