Sorry, I don't have any actual advice since I don't live in England. So I don't know what things are like over there.

But if it were my kid being threatened with a sharp deadly instrument in our school, especially by a child with known tantrum issues, "DP" would be permanently out of that school so fast he wouldn't have time to clean out his desk. I don't care who his parents are, they could be the president and the first lady for all I care, that kid's not going to be allowed to threaten my child with a deadly weapon any more. Not one single time more.

And if the school balks at expelling the child, the next people to hear about it would be the local newspaper. Then the local television station. Imagine the impact of a cute 10 year old on the screen saying, "He tried to stab me with the sharp scissors, but the school keeps him here even though Dad says he's dangerous."

Hey, now THERE'S an idea. Get the local TV station to tape a pre-interview with you and your son, and have the quote ready to play to the headmaster. Then have the TV station waiting outside of the meeting with the headmaster. I think it would make the meeting go much more smoothly in your favor, don't you think?

Oh wait. In the UK, you don't even have local TV stations, or do you? They probably don't go for sensationalist news stories like that anyway. Here in the US, our local TV stations would eat that stuff right up. It'd be in the top five stories of the night on the 6 o'clock news. How's that sort of thing done in the UK?