Frenck said:
What Halo Wars' writers don't seem to get is that there doesn't have to be an Arbiter during all times. Arbiters are created when the Covenant is in danger of falling apart either due to resistant future members (Hunters) or rebellious underprivilegded members (Grunts) and they are to vanish with the danger they were created to fight.
It would appear that you've read
Contact Harvest based on your mentioning of the taming of the Hunters and the Grunt rebellion, but I'm not sure, because about 50% of the Covenant story in the novel centers around the Minister of Fortitude, our main antagonist, who is calling the shots during the year 2531 and is also very aware of the threat to the Covenant posed on Harvest. The threat of the Forerunner's relationship to the humans, which clearly materializes in a rather public way when they uncover Forerunner relics.
In fact, I don't think there could be many examples of a better time to argue
for an Arbiter's existence than their efforts to take the first human world, Harvest. Even more so, now that we see concrete evidence of Forerunner property on the planet. I don't want to give away the story of the book, because it's easily the best one out of the five out right now, but it's pretty obvious to me the specific reasons why he would have an Arbiter involved in this process.
Humanity doesn't pose a threat to the Covenant either, not in a physical way at least. Truth's knowledge about them is dangerous, their existence is dangerous but their fleet and their weapons are laughable in comparison to the Covenant's arsenal. You can't create an Arbiter to either A) destroy Humanity or B) destroy the knowlege of their heritage. We don't know anything about the nature of the Grunt Rebellion to name one example. I'm pretty sure the Arbiter was used to kill their leaders and the cowardly Grunts who were left didn't want to put up a fight.
Firstly, we know a lot about the Grunt rebellion. We know that it started due to breeding disputes on High Charity amongst both Grunts and Jackals. We know that despite the creation of an Arbiter the Sangheili fleet resorted to glassing half of the Grunt's homeworld to put an end to the uprising. There's a lot we know about it. Not everything, obviously, but a significant portion.
Secondly, the humans take Harvest back initially, crushing the Covenant forces as hinted in
Fall of Reach and as depicted in the Halo Wars trailers. The human threat, at first, is very real because the Covenant underestimate them. The metaphorical threat, which is that the humans are "related" to the Forerunners, is even more real, because if that knowledge were widely known it would bring about the end of their religion. This is why Fortitude would likely need a fervent, devout zealot whose mission would likely end in death to lead the ground forces in the seizing of Forerunner property from human control.
An Arbiter is powerful, he is disposable and if our knowledge of the history portion of the fiction proves accurate, he's likely the reason that the Covenant end up winning the planet back and later destroying it.
