I recall a case in my town where 4 young men confronted on young man in a park.The lone ,man fled,but was knocked down and was being beaten.The lone man had a Buck folding hunter knife in his pocket.He used it,and one of the attackers died.
All I have is what was in the paper,but for that the young man was sentenced to five years,the DA"He brought a knife to a fist fight".Seems like self defense to me,and the surviving attackers deserve jail time.
A more recent case in my town,after an evening of drinking,a man decided to end his evening with a fight.One punch,the man who was hit died.Jail time,with good reason.I call it murder.
Not specific to Z vs M,if you are carrying concealed ,IMO,it is a very good idea to not be in a position where an unarmed man would attack you with a beating.
In other words,IMO,do not let your weapon give you courage to enter an altercation.
I think most LEOs would agree scuffling on the ground is a good way to be shot with your own weapon.If an unarmed man is beating you senseless,you may have to shoot him to survive,but you will have shot an unarmed man.
That is not a popular thing to do.
An equal suggestion of restraint to those who think fists are a good idea.The guy you punch may shoot you dead.