One of the most coveted and powerful weapons by Soldiers, Fixers and Agents is a Perennium weapon. They are not hard to make and the requirements to equip one is reasonable. The lowest QL which can be produced is QL 50, up to QL 200. Their attack rate is fast, and the damage beats pretty much any Rubi-Ka weapon.
Here are the items you'll need, all have to be quality level 50 or higher and the well known 80% tradeskill rule applies of course:
The Spirit Tech Apparatus: Short Muzzle/Long Muzzle/Double Barrel items can found on Mortiig dyna bosses. Each will determine what the weapon will become. Note that the Spirit Tech Apparatus must be at least 80% of the QL of the Nano-Charged weapon (which determines the final QL).