Not a weakness per se, but rather a lost opportunity for learning how to assert yourself. Violence is the purest form of assertion, and can be extrapolated into nonviolent aspects of life later on.

Being bullied (and fighting back) made me consider the philosophy of violence as a kid, and made me strong. It also taught me to stand my ground and take no shit from anyone, which was true in school, in the workplace, dealing with customer support, you name it.

I do not agree that violence is the purest form of assertion. On what basis did you judge purity, anyway? That seems like the sort of thing a violent person tells themselves in justification of their world view.