Unsharpened katanas, often referred to as "blunt" or "unsharpened" blades, serve various purposes depending on the context and intended use. Here are a few reasons why katanas may be unsharpened:

1. Training and Practice: Unsharpened katanas are commonly used for training purposes, particularly in martial arts such as Iaido or Kendo. They allow practitioners to perform techniques, kata (forms), and sparring exercises safely without the risk of serious injury. Unsharpened blades reduce the likelihood of accidental cuts or severe wounds during training sessions.
2. Demonstrations and Performances: Unsharpened katanas are frequently used in demonstrations, exhibitions, and theatrical performances. They allow practitioners or performers to showcase various techniques, choreographed fights, or historical reenactments without the need for live, sharp blades. Unsharpened blades provide a level of safety for both the performers and the audience.
3. Decorative or Display Purposes: Unsharpened katanas are also popular as decorative or display pieces. These katanas are often crafted with attention to aesthetics, featuring ornate fittings, detailed engraving, or unique designs. Unsharpened blades are considered safer for display purposes, reducing the risk of accidental cuts or injuries when handling or showcasing the sword.
4. Legal and Safety Considerations: In some regions or countries, there may be legal restrictions on the possession or use of sharp-edged weapons. Unsharpened katanas can provide an alternative for enthusiasts or collectors who wish to own a katana without running afoul of legal regulations. Additionally, unsharpened blades can be safer options for individuals who are less experienced in handling sharp blades or for environments where safety is a significant concern.

It is important to note that unsharpened katanas still require proper handling and respect. Even though they lack a cutting edge, they should be treated with care, considering their weight, balance, and potential for impact during training or demonstrations.