I think its also important to prepare yourself for the worst scenario possible. Set some rules for yourself to follow in case you are in a situation which is dangerous. If you are in a situation you need to stay calm, think clearly, do as they say, and try not panic. I watched a segment where a hijacker was interviewed, and he said that he murdered someone purely out of panic himself. This driver reached to take her belt off, he thought she was going for a weapon, he panicked and was high on drugs and shot her.
Now obviously we DONT want to be in this situation in the first place, so being aware is number 1. However, if you find yourself in a situation such as this its very important to know that you're dealing with an unstable person who is more than likely terribly high on drugs and is not thinking clearly himself/herself.
I personally think a weapon is dangerous as most of the time its taken away and used against you ... But if you feel better with it, then thats fine .. i couldnt have one due to road rage
