I want to be able to buy a common version of a weapon with no perk and then level it up with xp. once a threshold is hit it unlocks a perk node, which will let you go buy and place a perk from banshee. once you've unlocked all the perk nodes then you can pick a masterwork and once its master worked a unique perk slot opens up allowing you to place semi exotic perks like health bum on kill, rate of fire increase, or partial mag fill on kill.