To make a wooden sword stronger, you can consider the following techniques and tips:

1. Wood selection: Choose a hardwood that is known for its strength and durability, such as white oak or hickory. These woods have good resistance to impact and are less likely to splinter or break under pressure.
2. Grain orientation: Pay attention to the grain orientation when constructing the wooden sword. The grain should run parallel to the length of the sword, as this provides better strength and resistance to bending or snapping.
3. Proper shaping: Ensure that the wooden sword is shaped with appropriate dimensions and proportions to distribute the stress evenly along the length of the blade and handle. A well-shaped sword with the right thickness and cross-section can provide better structural integrity.
4. Reinforcements: Consider reinforcing specific areas of the sword that are more prone to stress or impact. This can be done by adding additional layers or strips of wood, fiberglass, or carbon fiber to strengthen the weak points.
5. Epoxy or resin coating: Applying epoxy or resin to the surface of the wooden sword can provide added strength and protection. This coating can help reinforce the wood, seal the grain, and make the sword more resistant to wear and moisture.
6. Regular maintenance: Proper maintenance is crucial to keep a wooden sword in good condition. Regularly inspect the sword for any signs of damage or wear, such as splinters or cracks, and address them promptly. Sanding away rough edges and applying protective finishes or oils can help maintain the sword's strength and longevity.

It's important to note that while these techniques can help improve the strength of a wooden sword, they cannot make it as strong as a metal blade. Wooden swords have their limitations, and they are primarily used for training and practice purposes. Always exercise caution and use appropriate safety measures when engaging in swordplay or training with a wooden sword to prevent injury.