Katanas are typically worn with the blade facing up in their scabbards, a practice known as "blade up" or "edge up" orientation. There are several reasons for this traditional way of wearing katanas:

1. Draw and Attack: Wearing the katana with the blade facing up allows for a smoother and faster draw when needed. With the blade oriented upwards, the samurai could unsheathe the sword quickly and bring it into position for an immediate attack.
2. Safety and Control: When wearing the katana with the blade facing up, it reduces the risk of accidental injury or damage, both to the samurai and those around them. The orientation allows the samurai to maintain better control over the sword during movements, preventing unintended contact or injury.
3. Etiquette and Respect: The blade-up orientation of the katana holds symbolic significance in terms of etiquette and respect. By wearing the sword with the cutting edge facing upwards, it is a demonstration of reverence and acknowledgment of the sword's lethal potential. It serves as a reminder to the samurai to exercise caution, discipline, and responsibility in handling the weapon.
4. Cultural Tradition: The practice of wearing the katana blade up has been passed down through generations and is deeply ingrained in the cultural and historical traditions associated with the samurai class in Japan. It is a part of the code of conduct and visual identity of the samurai.

It's important to note that the specific manner of wearing a katana can vary across different periods of Japanese history, individual preferences, and the context in which the sword is being worn.