If you were envied, why should you sharpen envy, and file up its teeth to an edge?
Why should they brighten their tomahawks and sharpen their knives against each other?
I know for a fact that Sergeant Martin had no less than nine pen-knives to sharpen.
You sharpen your wits on other people's, and you keep in touch with all kinds of opinions.
Twas unkind in my uncle to sharpen ...