Live By The Sword Die By The Sword.

51 And, behold, one of them which were with Jesus stretched out his hand, and drew his sword, and struck a servant of the high priest's, and smote off his ear. 52 Then said Jesus unto him, Put up again thy sword into his place: for all they that take the sword shall perish with the sword.

If you use a carnal weapon, you will die a spiritual death. Peter used the sword and than was rebuked. 

Ephesians 6:11-18

11 Put on the whole armour of God, that ye may be able to stand against the wiles of the devil. 12 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. 13 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.

14 Stand therefore, having your loins girt about with truth, and having on the breastplate of righteousness; 15 And your feet shod with the preparation of the gospel of peace; 16 Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked. 17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God: 18 Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints

You are not against your brother or some other fleshly person, but you are against an evil spirit. It is a spiritual war, you must use spiritual weapons, for defense and battle. If you use the fleshly weapons than you are venerable to the enemy. 

Verse 17 says

17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God: 

The word of God is the Truth, or the Bible. If we want to live and not fail God than we must lean not unto our own understanding but unto the Word of God. 

Hebrews 4:11

For the word of God is quick, and powerful, and sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart

His word is the single most deadly weapon in the world. 

If we want to live a spiritual, Holy life, than we must put down our swords and pick up his word.

Psalms 119:11 says 

Thy word have I hid in mine heart, that I might not sin against thee:

His word is a way to bypass sin, a way to live holy in an unholy world. 

It is where we look to for direction, doctrine, and reproof.

His Word is Truly our Sword and Salvation.