Taking a deep breath.
Imagine you are under an immense amount of stress. Carrying a weapon isn't going to change anything. If you were scared, it might help you a little bit, but stress is completely different. There is actually a thing called sensory overload, and it means that when you get really stressed, sometimes even the smallest thing like someone breathing can set you off into doing something you might regret. Carrying a weapon while under stress won't fix anything, and could cause you to hurt somebody.
Ignoring conflicts will not keep you from being stressed if you are currently stressed about something that does not even involve conflict. For example, maybe you are stressed out about you health exam. Ignoring conflicts isn't going to help you out at all. You're not even thinking clearly and your stress is only going to get worse if you do nothing about it.
Arguing with your friends is actually going to cause you to be more stressed out, and you do not want to amplify something you are currently trying to get rid of completely.
Taking a deep breath means that you will be able to close your eyes and allow oxygen into your brain. You will have a moment to calm down and think about what you are doing. Taking a deep breath has also been proven to help immensely when people are stressed or afraid.