I found the last Briefings of Episode 6. 2 are in the room where you fight the Last Guardian of Limbo, they're in the upper parts where there is a destroyed bdirge, one on either side. I don't remember all the exact locations of the others, but they are in Limbo and Shadowlands so look around in them thoroughly you'll find them. But I still need to know how to unlock the Amazon Chest and Legs.