As game theory indicates, both being selfish may not bring the best outcome to either side of a relationship, but being selfish can make one benefit most regardless to the action of the other person. Hence, in development of human society, we created laws (whose basic form is prohibitions) to prevent everyone being so self-orientated the society will harm. By so we can see that prohibitions are not the cause, though a very good indicator, to the lacking of virtuous people. During the process of building up basic social orders, some people may try to behave themselves beyond the requirement of laws for hope of better relationships, and those who responded or get responds will promote this change in larger scale more quickly.
Weapons work in the same theory, but in the opposite direction. Security is the status that no threats exist, and threat comes from one side being significantly stronger than the other, which is made by the existence of weapons (either physical or generalized). To make both sides equal, there are two obvious ways: one is to keep weapons from both sides, and the other is, however, give weapons to both sides. It is almost impossible to eliminate weapons without having any for those who want power will make their own on way or another, so the best solution to security is to give everyone enough weapons to defend themselves.
The relationship between subsidies and