Haven't seen anyone mention it, and if they have forgive my redundancy, but I just pulled an Avenger off a Legendary Wee War Loader (I think that's his full name). My other three pearls all came from loot midgets and I hadn't seen anyone mention this yet. So long story short, all those legendary dudes can drop pearls. Midgets may have a higher chance (who really knows?) but the loaders drop 'em too. Hope this helps in some way for the discouraged.