Re: Aggressive aikidoka
don't be too draconic on the poor boy. You haven't seen his view. I guess, I can understand him. Having seen those Bruce Lee, Jackie Chan and Steven Seagal movies (and all the others), now studying such a martial art, he wants to play around a show want he can do.
Nevertheless there is no excuse for not stopping after being asked for. And especially playing with a bread knife is very dangerous, even more than the frying pan. Twice I nearly cut off the top of my forefinger.
And do not forget most dojo have rules that it is strictly forbidden to practice or demonstrate techniques outside the dojo without self defence need or prior permission.
Very important: do never respond to his attacks. He might see it as an invitation to continue. Just stay totally immobilised.
Tell him again that you prefer training in the dojo, and what he is doing is not any fun to you. He can do on his buddies as they agree to, but if they want to be taken to the dojo they should not include you anyhow and it doesn't matter if they like it (or you) or not.
If that does not help, do the other things proposed. Tell the instructor. he might even get excluded from practicing in the dojo, stop the contract - actually he cancelled it then and mybe refuse him as partner in dojo.
Then there is no more contact and everything should be fine for you. If he really still comes for you, yes then the police might be the ultimate solution.
Again that behaviour is quite normal for young boys (from 13 to 30). Maybe not for all as I see from the posts, but for many of them.
They just have to learn their limits to get back to reason in time. Otherwise they just learn it later. You see,my father (only sometimes) even bullied me and my brother with his ju jutsu tricks from his youth and lone fighter training, until my younger brother, then 17 years old, replied with a low mawashi geri and broke my father's little finger. he was some 48 years at this point and obviously nobody stopped him before. But then it was finished. I just do not propose to give anybody a similar lesson unless you are good enough to be sure, it will not end up in a fight.