This is an idiotic way to accomplish this change.
I obtained TWO Blade of the Unmaker from the same Madness of Deathwing kill, and can no longer use either. We group-queued with over 20 members from our guild, and not a single rogue was present who would have used these items (big surprise: you give freebie welfare stage1 legendary daggers to every rogue - why do these even exist?). Yes, I vendored my previous weapon(s?), and I don't even recall what it was. No, I don't want to wait FOUR DAYS EIGHTEEN HOURS (in-game ticket reply time estimate) for a GM to give me back an item I will have already replaced.
Restrict future drops, but punishing players who already legitimately obtained the items is moronic. This change would have been far better accomplished by creating a new version of these items with a different item ID that is class restricted, and removing the old non-restricted version from the loot table. Maybe that requires a client-side patch, but that's still better than the implementation you decided on.
surprise surprise. this is blizzard's way of saying hunters havent dual wielded since forever and that you should probably look at what blizzard has flagged as a melee weapon for hunters. You should thank them for teaching you how to gear up too