A "spring steel katana" typically refers to a katana sword that incorporates spring steel in its construction. This means that the sword utilizes spring steel for specific components or elements within the katana design.

Spring steel is known for its excellent elasticity and resilience, making it suitable for applications that require the material to withstand repeated bending or twisting without permanent deformation or breakage. In the context of a katana, spring steel can be utilized in various ways, such as:

1. Tsuka (Handle): The handle of a katana, known as the tsuka, may incorporate spring steel for the tang or other internal components to provide added strength and flexibility.
2. Tsuba (Guard): The tsuba, which is the handguard of a katana, can be made from spring steel to enhance its durability and resistance to impact.
3. Fuchi and Kashira (Hilt Fittings): Spring steel can be used for the fuchi (collar) and kashira (pommel) fittings of the katana's hilt to provide strength and resilience.
4. Habaki (Blade Collar): The habaki, which is the collar that secures the blade into the hilt, can incorporate spring steel for added stability and retention.

It's important to note that the blade itself of a traditional Japanese katana is not typically made from spring steel. The blade is traditionally crafted from Tamahagane steel, which is a specific type of steel produced through a traditional smelting process in Japan.

A spring steel katana may be a modern interpretation or adaptation of a katana design, incorporating spring steel in certain components to enhance their performance and durability. The use of spring steel can provide added strength, flexibility, and resilience to these specific elements of the katana, contributing to its overall quality and performance.