What does "collection conqueror" unlock exactly?

I got “Guardians Bounty”, so I have those armor/weapon coatings and the SR 152 mantle emblems, but I fail to understand what the “collection conqueror” unlocked.
Any one know or is it for a future dated unlock?
Google search didn’t turn up anything either.

It’s still unclear to me how to even get it. Alot of my friends got it but I don’t.

It unlocks the Mark VI Helmet weapon emblem

According to Uny you’re supposed to get it for completing the 3 legendary campaigns in the MCC and it unlocks the Mark VI helmet weapon emblem

But it seems bugged then since I did that and didn’t get anything

Really? Nothing for getting every halo achievement? That’s what I thought it was originally for :confused: