We are saved by grace and grace alone.
The Sword of the Spirit
The Sword of the Spirit works exactly the same way it does with God Himself! He created by speaking. His Word is a word of authority. It does not matter whose mouth that word emits from. If it is His Word it will carry His authority. If you speak it, God's authority will work through it.
You were created in His image. You are supposed to be like Him, creating your own victory with your tongue. There are many verses in the Bible that state this. Remember that there was a sharp two-edged sword coming from Jesus' mouth according to Revelation 1:16? That is a picture of you, His follower.
James states that our tongues are to be a blessing!
The Proverbs say that life and death are in the power of the tongue!
It is a two-edged sword because it will cut in your own life as well as in the world surrounding you, both spiritual and natural!