What does Scripture mean when it uses the expression two-edged sword? How many times does it use this term?
A two-edged sword cuts in both directions—as opposed to a sabre, which is sharp on only one side of the blade. Nelson’s Complete Concordance of the New American Bible has seven entries. Ehud made himself a one-foot-long, two-edged dagger (Jgs 3:16). Psalm 149:6 speaks of God’s people as praising the Lord with their mouths and holding two-edged swords in their hands. Proverbs 5:3 says that the lips of an adulterous woman drip with honey, and her mouth is smoother than oil. Even so, “in the end, she is as bitter as wormwood, as sharp as a two-edged sword” (5:4). The same, of course, is true of an adulterous man. According to Sirach 21:3, “Every offense [sin] is a two-edged sword; when it cuts, there can be no healing.” Repentance is always possible but must begin with acknowledging why the person needs to repent.
Perhaps the best-known biblical reference is Hebrews 4:12, which describes the word of God as “living and effective, sharper than any two-edged sword, penetrating even between soul and spirit, joints and marrow, and able to discern reflections and thoughts of the heart.” The Book of Revelation’s author recounts a vision in which “one like a son of man” (1:13a) appears with a sharp two-edged sword coming out of his mouth (v. 16). The same author is later told to write to the angel of the church in Pergamum that “the one with the sharp two-edged sword says this” (2:12), rebuking the Christians there for several offenses.
Taken together, all these references except the first one above indicate the decisiveness of God’s word and God’s ways; they cannot be avoided or explained away. They will prevail.