Whether a single-edged sword is better than a double-edged sword or vice versa depends on various factors and considerations. Here are a few points to consider:

1. Cutting Ability: A single-edged sword, especially one with a curved blade like a katana or a scimitar, can excel in cutting techniques. The curved edge allows for a longer cutting surface, potentially making it more efficient in slashing motions. However, it's worth noting that a well-designed and sharp double-edged sword can still deliver effective cutting performance.
2. Thrusting Ability: Double-edged swords generally have an advantage when it comes to thrusting attacks. With a point on both ends, they offer versatility in penetrating armor or delivering precise stabs. Single-edged swords are typically not optimized for thrusting attacks, although they can still be used effectively in such situations.
3. Defensive Capabilities: Single-edged swords can provide advantages in defensive techniques. The flat or unsharpened side of the blade can be used for blocking or parrying an opponent's attack, providing a wider surface area for defense. Double-edged swords, on the other hand, require more precision and care in defensive maneuvers due to the risk of the opposing blade sliding along one edge and reaching the wielder.
4. Handling and Weight: Single-edged swords are often lighter and more balanced due to the weight distribution being focused on one side. This can make them faster and easier to wield in certain situations, offering better maneuverability. Double-edged swords may have a more balanced weight distribution along the length of the blade, which can affect handling characteristics.
5. Personal Preference and Training: Ultimately, the preference and training of the wielder play a significant role. Different sword styles and techniques may favor one type of sword over the other. Factors such as personal skill, experience, and familiarity with a particular sword type can significantly impact its effectiveness in the hands of an individual.

It's important to note that the effectiveness of a sword depends on multiple factors, including the design, materials, balance, and the skill and training of the wielder. Both single-edged and double-edged swords have been historically used with great success in different cultures and time periods, demonstrating that their effectiveness is influenced by the context and the specific requirements of the combat situation.