A malapropism is the substituting of one word for another, usually accidentally. The effect is usually comic. Both words are fairly similar in sound, therefore such substitution seems almost natural. The (18th century ) playwright Sheridan had a character in one of his plays named Mrs. Malaprop, who made such substitutions routinely, to much comic effect.

Possibly your sentence could be a malapropism. I can’t tell based on your info. For instance, supposed what SHOULD have been said was:

“Your reason, dear men, give thy reason.”

And supposed venom had been said instead of men. Then this WOULD be a malapropism.

An oxymoron combines two contradictory words. “A government organization” is such a term if you accept the humor–because governments are seen as disorganized.

In a pun, one word is used but at least two words are implied. If I say, “That’s not punny,” the word punny is used instead of funny and pun.

A metaphor occurs when one thing is compared to another.

“Shall I compare thee to a summer’s day?” In this line of Shakespeare’s, “thee” and “a summer’s day” are being compared.

Metaphor is a fairly broad term. There are many types of metaphors and sub categories of metaphors.The other terms cited are much more limited and specific.

here, the venom is compared to a person who has a reason for killing

hope i helped