Weapon balance mechanics

Does someone know, or could devs explain the process that is followed and the characteristics that are taken in account in order to balance weapons? Are all characteristics of the weapon taken in account when balancing it? (Not just the ones that we can see, also: how easy is to use a weapon in comparison to others, how popular is a weapon, the average damage per shot (weapons with damage radius), the effect of one weapon over another (fire/ice increase damage perks)...)