Here's why:
* "-ism" typically refers to a system, ideology, or doctrine. For example, communism, capitalism, feminism.
* "Brave manner" describes an action or behavior. While there could be a philosophical or ethical approach to bravery, there isn't a commonly recognized "-ism" for it.
If you're looking for a specific term, you could consider using:
* Valorousness: This emphasizes courage and nobility in action.
* Audacity: This suggests boldness and daring in the face of risk.
* Heroism: This implies extraordinary bravery in a specific context.
Ultimately, the best term depends on the specific nuance you want to convey.