Yes, clay-tempered steel is highly regarded for sword-making and is known for its desirable characteristics. Clay tempering is a traditional Japanese technique used in the production of katana swords. Here are some reasons why clay-tempered steel is considered good for swords:

1. Differential Hardening: Clay tempering involves applying a layer of clay to the blade before heat treating it. During the heat treatment process, the clay acts as an insulator, leading to differential heating and cooling of the blade. This creates a distinct hardening pattern, with a harder edge (yakiba) and a softer spine (mune). The differential hardening enhances the blade's cutting performance and strength.
2. Sharpness and Edge Retention: The clay-tempering process results in a hardened edge that can achieve exceptional sharpness and edge retention. The hard edge allows for effective cutting and slicing while maintaining a durable edge for longer periods.
3. Resilience and Flexibility: The softer spine of a clay-tempered blade provides flexibility and resilience. This allows the blade to absorb shocks and impacts during combat, reducing the risk of breakage or damage.
4. Visual Aesthetics: Clay-tempered steel blades often exhibit a distinct hamon, which is the visible line separating the hardened edge from the softer spine. The hamon adds to the visual appeal and artistic value of the sword, making it highly sought after by collectors and enthusiasts.
5. Traditional Craftsmanship: Clay tempering is deeply rooted in Japanese sword-making traditions and is associated with the iconic katana. The use of clay-tempered steel allows for the replication of traditional techniques and historical authenticity, appealing to those who value the cultural and historical significance of the katana.

While clay-tempered steel blades offer numerous advantages, it's important to note that the overall quality of a sword depends on various factors, including the skill of the swordsmith, the specific heat treatment process, and the craftsmanship involved. It is recommended to seek out reputable swordsmiths or knowledgeable experts when considering a clay-tempered steel sword to ensure the blade's quality and authenticity.