The Sword of My Mouth

Therefore repent. If not, I will come to you soon and war against them with the sword of my mouth.
-- Revelation 2:16 ESV; see also 1:16 and 19:11-16

Many symbols which reveal a spiritual truth in Revelation come from the sphere of a kingdom. One of those symbols is "the sword of my mouth." The picture involves a play on words. In OT Hebrew, people were slain with the "edge of the sword" which was literally the "mouth (pěh) of the sword (ḥereb)."  Isaiah made a play on these words when he wrote, "He made my mouth (pěh) like a sharp sword (ḥereb)" (Isaiah 49:2). Here, John accomplishes the same thing by changing the construction from "mouth of the sword" to "sword of the mouth." The "sword of my mouth" is a symbol for the words Jesus speaks. The words of Jesus are compared to a sword.

By comparing the words of Jesus to a sword, John reveals a spiritual truth about his words. His words are powerful. They can judge and give the sentence of death (John 12:48). In Revelation 2:16, the words spoken by Jesus will effectively bring judgment and death on those who follow Balaam and the Nicolaitans. We are not to think this picture refers to a bloody sword fight, but to the powerful sentence of a judge.  Likewise, in Revelation 19, Jesus does not engage the unbelieving nations in a bloody battle with a literal sword, but his word of judgment consigns them to eternal death (cf. 2 Thessalonians 2:8). His words are as powerful as a sword.

Lowery summarizes the comparison and its purpose with these words: "Symbols are commonly used to communicate abstract ideas in concrete ways. Revelation's symbols represent spiritual realities; thus the double-edged sword in Jesus' mouth (Rev. 1:16) represents power and truth, not an actual sword in his mouth."[1]

[1] Lowery, R., 2006. Revelation’s rhapsody: listening to the lyrics of the lamb : how to read the book of Revelation, Joplin, MO: College Press Pub. Co., p. 215.