A man that bears false witness against his neighbor is a club, and a sword, and a sharp arrow.
All Commentaries on Proverbs 25:18 Go To Proverbs 25
Athanasius the Apostolic
He that has been struck by a stone goes to a physician, but sharper than a stone are the strokes of calumny. For, as Solomon has said, “A false witness is a war club, and a sword, and a sharp arrow,” and its wounds truth alone is able to cure. If truth is set at naught, the wounds grow worse and worse.