Weapons certainly make violence easier. It takes much less courage and very little comparable strength for a person to point and shoot a gun and the further away you can be from your victim the braver you become and the less personal it becomes.
A gun turns a coward into a brave person -
The young man in the Sandy Hook shooting was so puny that a couple of those kids could have taken him out, his mother was a wealthy intelligent person and yet ignored any signs she should have seen and was totally irresponsible in that she failed to keep the weapons in a secure safe that he couldnt get access too - which means that anyone breaking into their home when they were out could have done the same - a friend of ours demonstrated how easy it was to open his safe with just a paper clip after being shown by a local State Trooper friend - he has now changed it to a biometric one
I would say that a huge percentage of typical UK Saturday night drunken pub brawls that currently end up with no more than some bruises and bloody noses would end up in death if the idiots had guns in their hands - yet many of these people when sober are perfectly sane & responsible and any criminal record checks would come up blank.
Many people can snap under certain circumstances and enough pressure has a strong impact on rational thought - towards the end of my first marriage I handed all of our guns (kept for game, clay pigeon and rough shooting) into the local police station as I was actually beginning to get plans forming in my head to shoot him - in fact at one point the only thing that was stopping me was something really silly.
If all households were to own guns would that make a lot of easy targets for the 'bad guys' to break in and steal them when we went out?