Oh and thanks to everyone else too who suggested things, the child proof locks on cupboards arent an option, as nothing is ever childproof with our kids. Little darlings they are, but we love them.

Hey Mony,

You would have found when entertaining that the little boys always want balloon guns and swords. I don't make guns, but as I do a lot of parties at a castle with a medieval theme, swords are unavoidable really. Most of the time the kids come armed to the teeth with swords made of wood and hard plastic and start fighting each other 'knight style'. The only way that I have found to get them to put the dangerous swords down is to let them do a parade wearing their swords (not really suitable in your situation I realise) and put the dangeourous swords in a box 'for safekeeping'. I then make the kids swords out of balloons and tell them "These are 'protecting swords', they pop if you attack people with them. They are for imaginary monsters and Im glad you're here to keep us safe" and start off the game with "quick save me from that dragon!" Surprisingly enough most of the time this works- especially with reminders "remember that's a protecting sword not an attacking sword"). If that doesn't work and they REALLY want to play fight each other I say that "It only counts when sword fighting if you get the other person in the belly button". If your children get too violent, the balloons will pop and they will learn to be more gentle. The first couple of times when they are just getting used to 'how much the balloon can take', only make replacement swords after a few minutes- encourage that child to get a drink of water and watch for 'pretend monsters' for the other kids. This will limit that child's space for a moment and possibly calm them a little before they go back to the game where they will want their balloon to last longer, so won't hit as hard. 

Please don't think I am making light of your situation, I would freak out if I saw kids playing with knives- it must stress you out a lot! But Im thinking if you continue to try to find a place to hide the knives and distract them with balloon swords- they may tire of the game eventually, and the knives may go out of their minds too. It might seem like giving them the swords is encouraging the fighting, but it's a case of it's better to playfight with something harmless like balloon swords than something so scarey as knives. Best wishes and I hope something works to help you with this soon xox