* The old schoolmaster used a ferule to discipline unruly students. (This emphasizes the traditional use of a ferule as a tool for punishment.)
* The ferule on the end of the walking stick provided a sturdy grip. (This highlights a different use of the word "ferule" as a metal or plastic cap.)
* The ferule on the end of the pencil was worn down from years of use. (This focuses on the ferule as a part of a writing instrument.)
You can also use "ferrule" in more abstract ways, such as:
* The ferule of tradition can be a powerful force, holding people back from progress. (This uses "ferule" metaphorically to represent a restrictive or controlling influence.)
* The company's new CEO hopes to break the ferule of outdated business practices. (This also uses "ferule" metaphorically to represent something that needs to be broken or changed.)