Honestly my best success with these strike exclusives is running the heroic playlist. I have all but the arc mantle, sabre warlock helmet, and taniks cloak. I've gotten 5 tread upon stars, 4 darkblade helms, 2 darkblades fusion rifles, 2 brothers gauntlets, and I think that's it on my duplicates. If the vanguard buff [i]doesn't[/i] affect those drop rates then I must be pretty lucky