Possibly some firestone vendor type npc to upgrade trash/vp loots, bearing in mind there is hardly any trash in DS. Not sure what essences of destruction are but it could be those? Then again maybe they are for the daggers.
Essences of Destruction are for the crafted items... it's possible they'll also be for the ranged slot upgrades, which I think would be cool, but unlikely since those would be higher item level.
I just haven't seen any type of firestone type item listed anywhere, or the vendor for it. I guess that's the assumption though.
it would not make sense to have the crafted mat do the same as the heroic firestone drop due to the fact this would mean either your crafting heroic level gear or you would be able to farm normal and get heroic items.
I really hope they don't do another firestone type drop unless they change how it works because the low, low percentage on firestones is rather frustrating. I haven't seen anything from the PTR that would be like that, but its still early so that could be what they are doing again and just haven't implemented it yet.