You two focus on one scenario too much. I suggest you try and generalize reasonably more. :P


Gun violence is essentially very dangerous. A criminal will have an initial advantage due to several factors. Surprise effect, planning and so forth. A criminal can be armed more easily when guns are not prohibited.
Gun violence can be avoided by getting rid of guns. Obviously not all acts of violence are commited with a gun, but reducing gun violence should be something to strive for.
Melee weapons are similar, but cannot be put into the same category as guns, as they are essentially omnipresent. They are also far away from being as lethal and they mostly serve purposes other than violence. Knives, for example, are mainly used as tools, not as weapons.