Weapons of Mass Destruction like Atomic Bombs and Nuclear Weapons.
I kind of understand why soldiers and police have guns as they are the protectors of the country and the one who who deals with the bad guys. Without weapons they are not that much to be feared and peace would be harder to keep. Whether you agree to this or not, Fear keep people in their places.
Atomic Bombs and Nuclear Weapons on the other hand are not weapons to keep people in their places. It's more like a weapon used by big countries to intimidate smaller countries into submission.
This I think is one of the many reasons why some countries do not evolve or grow as they are being limited by some big countries. Without these weapons, smaller countries would be able to "freely" make a decision for themselves