If you don't have a sharpener on hand, it's possible to sharpen a knife with another knife. It's important to note that this process could damage the knives and should only be done if necessary. Follow the steps below to sharpen your knife without a sharpener:
1. Place the blade of the dull knife against the spine of another.
2. Slide the dull knife up the spine.
3. Continue until your blade is sharp.