Where do we find these secrets items in campaign?

So I know in the campaign we have the lockers to earn for multiplayer customizations. So Far I have all the lockers that show on the map. But I was looking through all the items in the game view of the customize room and so far I see three Items that not seen in the campaign at all so far I played. Which the three items that are not unlock are which is the Infinity charm, Act of Genesis stance and Requiem Revengeance stance. I don’t know if anyone found them as it is a bummer that these three items says “Can be acquire in infinite campaign.”

If anyone has please comment on how you found it, or if 343 wants to clarify on these three items. Cause 343 place a skull in the final mission that had the last skull on the Silent Auditorium mission that wasn’t showing there was a skull on that mission till watching the collectible guide for the skulls.