"He made my mouth like a sharpened sword, in the shadow of his hand he hid me; he made me into a polished arrow and concealed me in his quiver." Isaiah 49:2
A sharp tongue cuts. There is a difference between speech sharpened by the Lord and speech sharpened by ourselves The mouth the Lord makes effective for good, is the one that speaks the word of God. It is controlled by the Holy Sprit and disciplined by prayer. When the tongue speaks words controlled by the flesh in a mouth undisciplined by prayer, those words do little good.
You are covered! God keeps you hidden in his shadow until the chosen moment comes for his word to be thrust with accuracy to deliver from Satan's lies.
A word for now: Let God shape your speech to pierce through hard unbelief by the spoken word. He can make your words go straight as an arrow to the heart.
Prayer: Lord sharpen my speech to penetrate at the right time to do good for others. I ask for the word of wisdom and of knowledge. Let me discern the time to speak and to deliver. Amen.