Ha: The Cutting Edge of the Katana

The ha is the cutting edge of the katana. This part of the blade is differentially hardened and therefore has far greater rigidity and hardness than the rest of the blade. Its HRC hardness is also different from that of the rest of the blade.

Ha: balance between hardness and keenness

It is important to have a perfect mix of hardness and keenness, because a blade that is too finely sharpened will be very thin and could chip after repeated cuts, or even break.

Many beginners in the field think that a very fine, razor-like edge is absolutely necessary for cutting. In fact, a niku edge (visually less fine) is even more effective, because it is more resistant and able to pass through tougher materials, even if it does not look that way.

How to sharpen a katana

If you want to learn more about sharpening a blade to restore the edge of your katana, or simply for your own knowledge, here is a video showing how it is done.

Sharpening stones for katanas

Stones for sharpening a katana are quite easy to find online. Japanese sharpening stones, known as whetstones, are specially designed for sharpening the blades of katanas and other Japanese swords. They are available in different grit sizes, allowing you to reach the level of fineness you want for the edge of your blade.

Precautions when sharpening

It is important to become familiar with proper sharpening techniques to avoid damaging the blade or compromising its performance. Sharpening a katana takes patience and precision to ensure an optimal edge and to preserve the beauty of the sword. If you are not sure you can sharpen your katana properly, it is best to call on an experienced professional.