When someone attacks us, it is not always possible to defend only using compassion & truth, sometimes aggression and getting angry is neccessary for defence. But if we use anger then we are no not in line with teachings.
Also, to defend the self, there has to be a self but self is an illusion, this also shows that defence is not possible.
If we are defending body, this means we have attachment to the body.
If we are defending verbal abuse this means we have attachment to mind states.
Attachment to body & mind, attachment to defence is leading to suffering.