He opens an oyster with a dagger. [ Proverb ]

What art thou? Have not I
An arm as big as thine? A heart as big?
Thy words, I grant, ate bigger, for I wear not
My dagger in my mouth. [ William Shakespeare ]

A dagger of the mind, a false creation, Proceeding from the heat-oppressed brain? [ William Shakespeare ]

Is death more cruel from a private dagger than in the field from murdering swords of thousands? Or does the number slain make slaughter glorious? [ Gibber ]

A man can no more justly make use of another's necessity, than he that has more strength can seize upon a weaker, master him to his obedience, and with a dagger at his throat, offer him death or slavery. [ J. Locke ]