In general, both sides of a sword blade are not equally sharp. The sharp edge of a sword is typically found on only one side, while the other side is often flat or has a thicker, blunter edge. This asymmetrical design is known as a single-edged blade.

For example, in the case of a katana, which is a single-edged sword, the cutting edge is on the outwardly curved side, known as the omote side, while the inwardly curved side, called the ura side, is typically flat or has a less sharp edge. This design allows for efficient cutting and slicing motions while maintaining overall balance and structural integrity.

However, it's important to note that not all swords follow this asymmetrical design. Some swords, such as certain European swords like the rapier or some historical Chinese swords, have double-edged blades, meaning both sides have sharpened edges.

The specific design of a sword's blade depends on its intended use, cultural traditions, and historical context. Different swords from different regions and time periods may have variations in their blade geometry, including the presence or absence of a second sharpened edge.

It's worth mentioning that the edge geometry and sharpness of a sword blade can vary based on individual preferences, specific sword types, and the intended purpose of the sword. Some swords may have more acute edges, while others may have slightly thicker edges for increased durability or specific cutting techniques.

When handling or studying swords, it's important to prioritize safety, familiarize yourself with the specific characteristics of the sword you are working with, and follow appropriate training and handling protocols.