How it works is that the first run of VoG you do each week (per character) will only give you loot from the encounter chests. So lets say you clear the raid on a Hunter this week, you would have the 4 loot drops from the encounters (opening the vault doesn't count as an encounter), but no Spoils. The next run you do this week on your Hunter will give you 5 Spoils per encounter instead of the loot drops. Its set up this way to give players a reason to run the raid multiple times on the same character each week.