Buy shit and break it down. If you have tons of weapons an armor, then you have tons of things that need to be upgraded. That's 18 energy/shards a piece. It's 150 marks for a weapon (3 energy) or 65 for cheap gear (3 shards), that's 900 marks per weapon and 390 marks per gear. Plus it takes literally 10 times longer to get enough marks to buy 20 mats compared to just farming them in a few minutes. It is a waste of marks for a handful of material, empirically so, there is absolutely no way it is useful unless you don't have any weapons or gear to upgrade. Out of my 24 legendary weapons, I only have 8 fully upgraded so far, that's 256 energy I still need, I still need 80 shards, and that's only for items I already have. Dark Below is coming, with tons of new armor and weapons, all of which will need 16 energy/shards to upgrade. Yet people are wasting precious items to dismantle into shards/energy by exchanging them for a tiny tiny amount of material that could be easily collected in 5 minutes. It's mindbogglingly stupid, I simply can't grasp the thought process that says "see this thing that is worse than this other thing? It's a great idea because it's so pointless!" The only reason I can think of is if they literally do not want any more weapons, or gear, ever again, yet if that were the case why the hell do they need common material.