RE'ing weapons does work. As a 400 armstech, I have multiple blue and purple weapon recipes from RE'ing. That being said, it's hardly ever worth it to bother trying to learn the blue and purple weapon recipes, even at level 50. They still don't have mod slots (barring an augment slot on the rare crit), meaning there's no room for upgrading their already sub-par stats. To get the blue recipe for the Fusion X-Blaster (Armstech 400), it took me about 60 RE attempts. The 3 purple recipes branching off of that blue recipe took approximately 10-15 RE attempts each. Good luck if you decide to stick with Armstech, but IMHO it's a nearly worthless profession.