Is it actionable and if so how serious? If there is genuine danger to your life or long term well being (like, if the dude just wants to give you a beat down, these are not the instructions, I've had a stalker firebomb my house, this is advice for if it's at that point) then you may need to make yourself comfortable with the idea of maybe doing time, the law will not help you, if contacted they'll do nothing and if you defend yourself they'll punish you for it. Does this person know where you live? If so, home defense, keep your doors locked, barricade windows, if your door knob is metal you can hook it to jumper cables and a battery, if there's a vestibule get a chain lock so you can open it enough to flood the room with bear mace, if you have a hallway use fishing line to make trip wires at odd angles and height so someone else can't move through the hall as easy as you. Turn out all the lights cause you know your house better than them in the dark and keep a weapon nearby, something blunt like a wooden bat or piece of rebar, metal bats are hollow and don't hurt much. Do not use knives ever.

If you're out and about, don't go alone, have people around who preferably can fight. Any hard metal object that you can carry to use as a bludgeon is gonna be the best weapon you can have.

Next thing is, do you think this guy will let off? Cause generally if they get fucked up the first time they're gonna come back harder the next. If there is a fight, it's best to try to have the guy leave it with their pride intact, easier said than done but at least if you come out on top.dont be gloaty or get in any more shots than necessary. I wouldn't do anything between bruises and a hospital stay, you don't want a dude who's only gonna be hurting for a day or two brooding about it, if there's gonna be brooding make it for a long time and over an injury that will.make next time harder for them cause its still just buying time

Now, it's usually not such a zero sum game, diplomacy will get you the furthest although you may need to swallow your pride and tell.the other dude whatever they wanna hear. Have a mutual be a go between. Do what you can to diffuse it and avoid things escalating, it's better to just give the baby his bottle even if it's humiliating, you live to fight another day and anyone who goes around threatening people will bite off more than they can chew one day, but that ends with one person in the hospital or morgue and the other in prison. Don't let it get to that point at ALL costs but if it can't be avoided, your self preservation is worth an assault charge.