If I was living in an outlying area, with my kids, I would want a weapon in case I needed to defend them from attack. But in a built up suburban area, I agree that it seems unneccessary to own one. But afaik, while it is wrong livelihood to earn one's living by selling weapons, owning one for personal use in an emergency isn't the same thing as trading in them. Just as Buddhists are allowed to purchase meat from a butcher, but aren't allowed to earn their living by being one. As for what the suttas say about a layman owning a weapon - I can't answer that one, and would be interested to hear if anyone knows.
Then the Blessed One, picking up a tiny bit of dust with the tip of his fingernail, said to the monk, "There isn't even this much form...feeling...
perception...fabrications...consciousness that is constant, lasting, eternal, not subject to change, that will stay just as it is as long as eternity."