Is picking on the weaker man an idiom?

"Picking on the weaker man" is not a commonly recognized idiom. It's more of a common phrase that describes the act of bullying or targeting someone who is perceived as weaker or less powerful.

Here are some similar idioms that convey a similar meaning:

* Bully the weak: This idiom directly refers to the act of using power to intimidate or harm those who are less powerful.

* Pick on someone smaller than you: This idiom emphasizes the unfairness of targeting someone who is less able to defend themselves.

* Kick someone when they're down: This idiom refers to taking advantage of someone's weakness or vulnerability.

* Pick a fight with someone who can't fight back: This idiom emphasizes the cowardice of attacking someone who is unable to defend themselves.

While "picking on the weaker man" isn't a formal idiom, it clearly conveys the concept of targeting someone who is vulnerable, making it a powerful and widely understood phrase.