@LockeKosta Form Weapons are supposed to be from Las Vegas enemies level 71+, but perhaps any rare enemies from an emergency code that can spawn on Las Vegas also contains the drop.
Aura Weapons are supposed to be from level 76+ Chrome Dragon, however our max leveled enemies are 71. I see from the Quest log that the Aura weapons are dropped most in Free Expedition maps and the Daybreak SHAQ quest.
There are also exceptionally rare drops from Gal Gryphon, but I am not sure what would be best to farm him.
It may be that all level 76-80 drops are a part of this NA port of the game, which means Banser (rare variant of the Fang wolfie from forest) also drop the silver doggo13* weapons