Our Lord (Yahshua) is known as the word as seen in John 1:1-14 and it is this word that is the sword of division. The truth found only in Christ separates us from the flood of lies, in fact Jesus even said He came not to bring peace but a sword (Luke 12:49-53) I am come to send fire on the earth; and what will I, if it be already kindled? But I have a baptism to be baptized with; and how am I straitened till it be accomplished!  Suppose ye that I am come to give peace on earth? I tell you, Nay; but rather division: For from henceforth there shall be five in one house divided, three against two, and two against three. The father shall be divided against the son, and the son against the father; the mother against the daughter, and the daughter against the mother; the mother in law against her daughter in law, and the daughter in law against her mother in law.

The whole armor of God offered to us in Ephesians is very needful for those who walk in faith, because it is the word we speak that causes division between the truth and a lie. It is the difference between the light of Gods truth verses the darkness of unrighteousness! (Ephesians 6:10-17) Finally, my brethren, be strong in the Lord, and in the power of his might. Put on the whole armour of God, that ye may be able to stand against the wiles of the devil. For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.  Wherefore take unto you the whole armour of God, that ye may be able to withstand in the evil day, and having done all, to stand.  Stand therefore, having your loins girt about with truth, and having on the breastplate of righteousness;  And your feet shod with the preparation of the gospel of peace; Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked. And take the helmet of salvation, and the sword of the Spirit, which is the word of God.

The word of God is the best defense a christian has in this life, and is as a sword to keep the enemy of our soul at bay. The day will come when the nations will be divided by the sword of the words our Lord will speak, as He will come back as Lord of Lords and King of Kings riding on a white horse arriving with the armies of heaven (Revelation 19:11-16) And I saw heaven opened, and behold a white horse; and he that sat upon him was called Faithful and True, and in righteousness he doth judge and make war. His eyes were as a flame of fire, and on his head were many crowns; and he had a name written, that no man knew, but he himself. And he was clothed with a vesture dipped in blood: and his name is called The Word of God. And the armies which were in heaven followed him upon white horses, clothed in fine linen, white and clean. And out of his mouth goeth a sharp sword, that with it he should smite the nations: and he shall rule them with a rod of iron: and he treadeth the winepress of the fierceness and wrath of Almighty God. And he hath on his vesture and on his thigh a name written, KING OF KINGS, AND LORD OF LORDS.