To clarify for you. If you do normal Crota you do not get ARMOUR drops off hard. Only weapon drops the armour is from the normal loot table and that gets taken away once you do normal.
Google loot tables for crotas end! There are drops specific to normal and hard but it's only weapons! Armor drops on hard if you run normal first. But if you get the material chests on normal you will not get them on hard also if you beat the deathsinger on normal she won't drop anything on hard. Just ran normal all the way through last night then got to deathsinger on hard still got armor at bridge
Better yet, beat it on hard and you get [b][u]both[/u][/b] drops at the same time.
Reduces the chances of getting doubled rewards (like say, getting a Legendary Non-Raid Hand-Cannon on Normal and then getting it again on Hard)