It was impulsive, it was angry and it sounds like it was very frightening. I can't advise you, because I wasn't there and I don't know how well he got the message that this was a dangerous thing to do.
Niece is too young to know what is dangerous andwhat isn't. So, in a way, is difficult child 2. The trouble is, he IS bigger. If he were an extra-large 5 year old, what would you do? How would you handle tis? How would you prevent a recurrence?
I think the best thing you can do, is to prevent recurrences. YOu can't judge a difficult child by his chronological age. Instead, you need to keep in mind that ongoing supervision is needed, until you are confident that a certain level of social responsibility has been reached.
For example - difficult child 3 loves to go bike-riding. His friend (10 years old) invited him to go fishing with a group of 10 year olds. difficult child 3 is 15. Why on earth would I not let him go?
There was no adult with them, this was just a geroup of boys, decent kids really, hanging out together. Surely I could leg difficult child 3 go with them? They don't tease him, they don't bully him.
I didn't let him go alone. Instead, I went with them but made myself useful by buying some bait and having some tools with me. I stayed out of as much of the social interaction as I could, but I was glad I was there because a few times difficult child 3 began to get upset because he was misunderstanding some of the interactions with the other boys. If I hadn't been there, difficult child 3 might have got angry and started a fight, or he might have managed to hold his temper but been miserable and also not learned anything. An example - I had bought a packet of cheap lures. I gacve one to one of the boys. When we were leaving, and the other boys had given up fishing and swimming instead, difficult child 3 began to make a big fuss about wanting the lure back. We had other lures, this was simply a matter of not wanting to lose something that I had brought, and which therefore belonged to our family.
If I hadn't been there, it could have been a nasty scene. Instead, we were able to leave, and leave without the lure. Over time since, difficult child 3 has been able to accept that it's OK to have left the lure with the boy, who will get a lot more use out of it that we would.
Because I tagged along, a potential negative experience was able to be identified, avoided and even turned into a positive one.
difficult child 3 is 15, but as far as social capabilities go, I can't let him wander off on his own without putting in a lot of careful checks and rules. In other words, he's 5 years old, socially. Very vulnerable. And so are any other people who try to interact with him, not knowing this.
SO what I suggest - depending on your own knowledge of your son, of course - is maintain a high level of supervision and also use your ability t intervene before a problem escalates, to turn them into positive teaching opportunities.
A difficult child is, by definition, not normal. Normal rules don't apply. We are needed to be much more hands-on. It's not good, it's reality.
I hope this can help.
Marg