I keep my blades in one of those TI wall boxes out of reach, and I did think of putting a small padlock on it, but after consideration I went for an approach similar to Bruno's. If you forbid/hide/exclude, the way a child's mind works you're instantly introducing something mysterious and attractive to them. Their curiosity will drive them to access them when you're not looking.

I reckon there's a lot to be said for introducing them to razors in a controlled fashion. Explain what they're for. Let them see how you respect the blade. Show them when you nick yourself to demonstrate how easy it is to hurt yourself by accident, even if you're paying attention.

Then establish the boundaries. E.g. no touching when Dad's not here. Kids are pretty quick on the uptake with cause and effect!

Both my children (6 and 3) have seen me shave. Both have seen me hone. Both have seen the 'special' razor that Mummy bought Daddy for their 10th anniversary There's no curiosity, it's pretty boring to them now. And they now understand to stand just outside the bathroom to talk to me during a shave, even when the door is wide open.

The last time I cut myself a few months ago (on the finger), I deliberately showed them and explained what happened and why. My wife then got her doctor bag out and patched me up. We made more of it than if it had just been my wife and I (in fact, she would have told me to deal with it myself unsympatheically ), but the result was the important thing -- my kids see a potentially dangerous objectt which holds no mystery to them, they understand it needs respect, and they're really not that interested in it now the mystery has gone.