Dual blade masks - from what gashapon?

I am curious as to where you get them. I think a few of us would like to try this out on our Night lords and Shadowers, so please post some facts here if you got em!

i believe that the masks are non-trade-able and also are given out by quests/job advancements or something only related to DB.... though im not to sure so dont take my word on it

Yes, but they also announced them to come from gash with better stats then the ones from DB quest. Either they are thief equips, making me drool for one, or they are dual-blade only like it says on the kataras.