In Halo 5 Guardians i wasnt awarded a Prophet Sword after completing the Legendary Campaign Mission 1 after shooting all the 7 knives and killing the Bosses. I was playing with the sword in the Campaign but it never ended up in my account afterward. what did i do wrong?
You didn’t do anything wrong. The campaign just doesn’t do anything for your REQ collection, which is multiplayer-only. Activating the Easter egg in the first mission won’t give you the certification for the Prophet’s Bane, nor will it give you any. The only way to get it is through buying Gold or better REQ packs.