Which part of the body is not generally considered a weapon but can be used if needed?

The head is often not viewed as a traditional weapon in martial arts, as it does not possess the striking capabilities associated with the hands, feet, or knees. However, in certain situations, the head can indeed be utilized effectively as a striking tool. Techniques such as headbutts demonstrate how the skull can generate significant force against an opponent. Although using the head is less common and generally more hazardous due to the risk of injury to oneself in comparison to the other body parts listed, it showcases the versatility of martial arts techniques.

Other options like hands, feet, and knees are frequently trained and categorized explicitly as tools for striking or defensive maneuvers. Their use is systematic and widely recognized within the context of martial arts training, making them conventional weapons compared to the head.