Bungie likes to take away content, what do you expect? Seriously tho, there is one Blade of Crota during the Fist of Crota mission. It's a little dumb that the completion of this bounty is only possible by repeating a single story mission 3 times, even if you go to orbit immediately after killing the Blade of Crota. It's tedious and not well thought out. They should have allowed the Blades of Crota to still randomly spawn on the moon or something, seeing as how that's the Hive's 'domain'.