lazyarse I think probably police is the way to go with 14 year olds and actual violence (rather than just "he said this and I said that" reported stuff which between kids will would probably a waste of police time unless it was inciting others to violence or racism etc.)
Assault is assault and a 14 year old assaulting another 14 year old is the same as a 24 year old assaulting another 14 year old.
I agree the axe thing is nowhere in the realms of normal, just that really just intervening by telling a child or teen they are a little shit is only ever going to make things worse (or at absolute best achieve absolutely nothing at all).
I have twice talked to parents when I thought my kids were being picked on (DD was called a "Bloody Foreigner" and DS1 pushed and threatened)) and it has both times turned out to be not quite the situation I thought it was, so I am very glad I approached it diplomatically, or we'd have fallen out with the parents when my kids were not blameless either
DD had called the boy a "Stupid Farmer" and he retaliated with "Bloody Foreigner" - he is a farmer (well a farmer's son) though definitely not stupid and who knows how that came to be an insult, but it is clear it was meant as one in the moment, and she is a foreigner (well, a foreigner's daughter)and he apologised but said he couldn't think of anything else nasty to say back as he couldn't think of anything bad about DD! His mum and grandma actually cried when I told them what he had said to her as they had faced prejudice when they moved here from East Germany 25 years ago!
In DS's case it was as above and the boy was retaliating physically after weeks of verbal teasing and one of DS's friends damaging his school bag. Physical retaliation is never OK (he did knock the boy who was the main protagonist actually doing the teasing flying and he ended up being taken to A & E after hitting his head on the floor, but he was OK), but it meant that actually IMO the other 3 boys (including my DS who stood by and sometimes laughed and did not set himself apart from the others) were more in the wrong. We also found out that the poor older boy was losing his hearing (nobody other than his family and teacher knew at that point and he didn't have hearing aids, but the boy knew himself) and his younger brother, who he is usually inseparable from around the village - was due to go into hospital for a series of operations - again none of the teasing boys knew, but it made the lashing out so very easy to understand and be sympathetic to.