Having the Crux of Crota will drastically improve your chances of getting the Husk of the Pit from the Blade of Crota, which would be appropriate considering there is only one left in the entire game. Alternatively, having a fully upgraded Eidolon Ally (with everything except the final node fully unlocked) in your character's inventory would in turn drastically increase your chances of getting the Crux of Crota. I believe this is appropriate given the fact that the drop rate is ridiculously low, and players can only attempt this once a week per character (there are people who have done this every week since it became available and still not obtained it). This would make it so that provided you've already beaten the odds once (by getting Crux) or that you've put a significant amount of effort into your quest (upgrading the Eidolon Ally), the game will be more lenient with you in the final roll. Well, either that or let people try for the Crux more than once a week. One of the two.