Yes, swords can dull over time with regular use or improper maintenance. The process of a sword's edge becoming less sharp is called dulling. Several factors contribute to the dulling of a sword:

1. Wear and Tear: With repeated use, the cutting edge of a sword comes into contact with various materials, such as targets, armor, or other blades. This contact can cause microscopic damage to the edge, resulting in a gradual loss of sharpness over time.
2. Friction and Impact: During cutting or striking actions, the edge of a sword experiences friction and impact forces that can cause deformation or chipping, leading to a dulled edge.
3. Corrosion and Oxidation: If a sword is not properly cleaned, dried, and maintained, it can be susceptible to corrosion and oxidation. Rust or corrosion on the blade can hinder its cutting ability and result in a dull edge.
4. Improper Cutting Technique: If a sword is used improperly, such as striking hard materials or using excessive force against unsuitable targets, it can accelerate the dulling process.

To maintain the sharpness of a sword, regular maintenance and care are necessary. This includes proper cleaning, drying, and oiling after use, as well as periodic sharpening to restore the edge. Sharpening should be done by an experienced individual or a professional to ensure the proper angle and technique are employed, as improper sharpening can damage the blade further.

It's important to note that different types of swords and their respective materials may vary in their resistance to dulling. Factors such as the quality of the steel, heat treatment, and overall craftsmanship can influence how well a sword retains its sharpness over time.