Interesting topic. As you mention, I think the difference is in the values and discipline that are taught along with the art (both martial art and the use of firearms). If responsibility and the conscious use of firearms are taught along with the subject of firearms, I think we could start talking to children about them from the age of 8-9 (without allowing them to use them), then teach them to use them during their adolescence and now, when they reach the age of majority, allow them to use them and cut them. It seems convenient to me especially to prevent rapes, femicides and kidnappings of girls. I would definitely feel more relaxed if my daughter knows how to use a gun and can carry it to defend herself in case some man wants to take advantage of her.
Also, as you rightly mention, it is important that psychological testing be done to determine if the person is mentally stable before allowing them to carry guns. Working on mental health issues and awareness in schools is also part of prevention and a mental health system accessible to the population is vital to prevent school shootings.
The problem is not the guns, it is the mental health system and the values we transmit to the new generations. That is my opinion.🫡