You really do have to be careful with the bigger ones. You have no idea how many things around you are made of steel or iron. I have a 2 inch by 1 inch square neodymium magnet. I was trying to wash the magnet in the sink. Up until that point in time I had always thought the sink was made of porcelain. I heard what sounded like a gunshot. The magnet was no longer in my hand. I was totally dismayed at the time. Looked around for it. There it was sticking tenaciously to the sink. I didn't get hurt. But I can definitely see how you could get hurt with one of these.
I own four 2 inch by 2 inch by .50 inch square #36 neodymium magnets. They were part of a device that I came up which I was going to patent about 25 years ago. The magnets were ranged in a way that it would pull one or two Tesla. The device could be configured to produce AC or DC high voltages with high amperage which would have run electric motors for electric cars. I abandoned the project because in theory it should have worked very well. The reality was I could not have been able to make it work as planned. The issues were: too much noise, too much magnetism pulling everything in sight that was metal, and you could not get high amperage or voltage out of the device.