Proverbs 27:17 As iron sharpens iron, so one person sharpens another [his friend -KJV].
Do you have difficulty sharpening your kitchen knives. I do. Some knives are made of an alloy that is too hard to sharpen. They last a good while if used carefully but become blunted. Really good kitchen knives are very expensive. A good chef has his own set and guards them carefully. Apparently, each cook will sharpen their knives differently!
The Bible proverb relates the way, in ancient times, an iron blade was sharpened by another. It must have required a great deal of care and patience. So, our actions and words can improve, sharpen our friends – or blunt them! Our communication with others needs the care and skill of our Lord Jesus through His Holy Spirit.