I was watching the original karate kid with my son the other week. Mr Miagi said the best way to block a punch was to not be there when it landed.
I think if you or your friend are this concerned about their personal safety, perhaps you should just stay home.
I have to agree carrying a weapon is fear related, not prudence. You can always justify things by saying what if this happened, then I would be protected, but in reality that rarely happens, and even in the cases it does, the user is rarely able to protect themselves.
Police statistics point this out over and over again. Even with their level of training, they often fail in the line of fire. How many shows have you seen where trained experienced officers are unable to either get to their weapon, or miss their target.
I have seen reports where over 30 rounds were fired by police at a single target, and they all missed.
Fear, panic, and the rush of emotion that surely comes in that situation can not be trained for effectively by the average home user.
I really am not directing this at anyone, and in no way really fault anyone for their beliefs as I hope I am not faulted by mine, but I do sincerely believe most people simply take comfort in the fact they have a weapon, and the reality of it is, in a life threatening situation, more often than not they fail to defend themselves well.