The rings on a "nine-ring sword" have several possible functions and purposes. Here are some commonly discussed reasons for the inclusion of rings on a nine-ring sword:

1. Improved Grip: The rings provide additional points of grip along the sword's handle, enhancing the wielder's control and stability. The rings allow the hand to secure the sword more firmly, preventing slippage during combat or handling.
2. Versatile Handling: The rings on a nine-ring sword can offer versatility in how the sword is held or manipulated. By placing fingers through different rings, the wielder can vary their grip, adjust their reach, or change the positioning of their hand for different combat techniques or styles.
3. Weight Distribution and Balance: The rings can affect the sword's weight distribution and balance. By adjusting the placement of the rings along the handle, the swordsmith can fine-tune the balance of the weapon. This allows for improved handling and maneuverability, potentially optimizing the sword for specific fighting techniques or preferences.
4. Symbolic or Cultural Significance: The rings on a nine-ring sword can carry symbolic or cultural meaning. In some cases, the number nine itself holds significance in various cultures, symbolizing completeness, power, or auspiciousness. The rings may represent these qualities or connect to specific cultural or spiritual beliefs.
5. Aesthetic Appeal: The rings on a nine-ring sword can serve as decorative elements, adding visual interest and enhancing the sword's appearance. They contribute to the overall aesthetic appeal of the sword, making it visually distinctive or unique.

It's worth noting that the specific reasons behind the inclusion of rings on a nine-ring sword may vary depending on the historical period, cultural context, and individual swordsmith's preferences. Different theories and interpretations exist, and the inclusion of rings can be attributed to a combination of functional, symbolic, and artistic considerations.