You will probably hate me for this but I got it on the first Blade of Crota I killed. I wasn't even trying to get it, I was running The Wakening on 30 for the bounty and noticed a Blade on my way to the Temple. Killed him as I had the Blades of Crota bounty active and figured I'd get the first one out of the way and Husk popped. Keep trying, you will eventually get it.