This is a hypothetical thing, for the most part.
To preface, my father has a rental property that also serves as his brothers home. Half of the property is rented, to at this time a good tenant. The other half (its a duplex) is where my uncle lives, and by contract, can live rent free until he dies (Long story, I wont go into the details), essentially my dad supports my uncle as well.
There are alot of undesirables that comes in and out of my uncles, all either drunks or on drugs, and my dad, who is going to be 64 has to run them out on a weekly basis, sometimes with police assistance. For the most part, these guys are just loud but leave, but my dad keeps making the statement that he feels one of these days he will be stabbed or attacked dealing with these issues, and I try to go with him whenever I can to be of assistance. Also let it be known that due to a shoulder injury, my fathers left are is practically useless
So onto the scenario.
Say we are at the apartment, and we have to run out one of the undesirables, but this guy is just going crazy, the police are called and could be minutes away. The guy grabs a weapon, and starts for us (for sake of discussion, a knife or a baseball bat) . Knowing that the weapon could be used as a deadly device, and we are unable to get out of the place I draw and he drops the weapon, at which point, he keeps coming towards us. He is ordered several times to stop but refuses and advances farther, say within 10 feet or so. What do you do? The fear is that maybe this subject maybe advancing in an attempt to disarm and use your weapon for his gain.
For another part of the discussion, say he is unarmed but comes as a threat. He is getting loud and maybe violent, at what point would it be justified in pulling a weapon?
In both of these we have to assume that my father and myself are the only to capable of defending anyone, my uncle is only 100lbs and frail, both my father and I are both 5'8"-5'9", both around 230.
In Ohio, self defense is allowable to defend yourself or another as long as the other would have had the right to defend themselves in the first place. We also have the castle doctrine, but in this case that would be null since that is not our residence.