I will hit anyone at all in self-defense - elderly, female, infirm, child, whatever - if it’s genuinely necessary to ensure my own safety, and I can deliver a blow proportional to the threat. If an old and frail man is trying to punch me, I’ll accept the blow rather than defend myself with a strike that may inflict serious injury. On the other extreme, if a small child had somehow grabbed Daddy’s gun and was pointing it at me, I would deliver as hard a blow as required to make him drop the gun; at last resort, I’d attempt a fatal one.
All of the above, though, pre-supposes that every other option has failed. Flight (leaving), evasion (dodging), persuasion - all have either failed or are clearly unworkable. As a last resort, hitting can be “okay” against anyone, provided the hitting is proportionate to the theat posed. But I don’t believe hitting is ever okay as anything other than a last resort.
As to the idea of hitting someone for reasons relating to honor: I’m a civilized man, and was raised to believe that honorable, civilized men abhor violence. I can’t imagine the slight to my honor that would be redeemed or mitigated through the use of violence. Oh, it might make my friends and family understand why I’d used violence - but it would still be a lapse of character.
Slight hijack, but isn’t this a bit broad? I have no problem with killing slaveowners - even the “humane” ones claim to exercise absolute ownership over another human being, and act on that belief. They deserve whatever they get. But what constitutes “supporting” slavery? I may abhor the beliefs of a pro-slavery newspaper editor, but so long as he doesn’t own slaves himself, I can’t support killing him for speaking his mind. More, I’d feel a moral obligation to defend the man if I could.
Further - do the family members of slaveholders “support” slavery, by refusing to reject their slave-holding family members? This takes us down an ugly road fast. There were women who owned slaves in their own right, I’m sure, but most women (especially wives) had little agency of their own in the antebellum South - I’d hate to see them killed for the sins of their husbands. And as for children - well, they’re children.