Article: Like the rods, these tapered triangles are designed specifically for serrated knives. Due to the shape, they tend to work best on knives with V-shaped gullets. The process is almost identical to the rod-shaped method described above, except that you rock the edge of the tool back and forth along the bevel instead of rotating it. If you would rather not buy a single-purpose tool, you can buy a few cheap dowels from a hardware store instead. Find a dowel that sits in the knife's first scallop without wobbling, then wrap a piece of emery cloth most of the way around the dowel. Hold the cloth in place with your finger, and sharpen carefully and slowly. Switch dowels to match the size of the scallops as you move along the knife. Use a round dowel for a knife with round scallops, or a square dowel for V-shaped scallops. This is a difficult and unreliable last resort, but it is possible. Hold the knife spine securely against a hard surface and tilt the blade so the beveled edge is on top. Bring the corner of the sharpening stone to the scalloped edge and use it to sharpen the edge, rocking it back and forth to cover the full area of each scallop.

What is a summary?
Use a triangle-shaped sharpener. Make your own tool from emery cloth and dowels. Sharpen with a square stone.