Instead of relying on a person to store a deadly weapon safely, we would be a step closer to eliminating violence as a result of misuse if the weapon itself were designed to be safe.
Using existing technology like PIN Code unlocks and NFC tags to make weapons more sophisticated reduces the likelihood of misuse, as only the person who knows the code would be able to use the weapon. Almost every device that contains personal information has some form of personal lock that prevents or delays misuse to some extent. This should be a simple manufacturing requirement for deadly weapons.
Making weapons more sophisticated would increase manufacturing costs a bit, but this would be worth it considering the increased safety in our communities.