Since someone decided to make a favorite Halo fact I decided to try the opposite. So what would yours be? Would have to say mine would be that they retconned the Covenant over the years from being able to fully glass a planets just taken out small areas. It felt in the older lore that it added more weight to the actual battles that took place during the war.
That and the fact humanity has been doing just fine after a 30-year war that devastated them so badly.
I think what you mean is that: older Halo Lore like that of the Unggoy Rebellion depicted singular ships absolutely devastating large areas. And I have to agree. It seemed like older ships just seemed more powerful. I was under the impression that a Covenant Excavation Beam was almost like a large scale nuke. It strikes one point and sends a wave of destruction that covers the better half of possibly several miles at the very least. Now it just seems like the extent of the damage just isn't as great.
Take Reach for example; when Kat warned Carter about the increased radiation flare nearby, I was under the impression that building was about to come down because of how close
it must have been for her to be that worried. Playing through the mission would show you that the Covenant were roughly a half a mile out on the other side of the city just Glassing it every now and then. So for one to just drop right on top of the remains of Noble team and then for ONE
Phantom to be able to just fly around an area that is being Glassed, well it just doesn't seem quite as powerful as we were lead to believe. In fact, it honestly seems more like Gears of Wars Hammer of Dawn. It's powerful where it strikes, but doesn't do much just a little bit out of its reaching point.
So, for it to be that
weak, it must honestly take so many
ships to Glass an entire
Now for the point of Humanity flourishing so well after a 3 decades long war that almost eradicated them from existence?
You have to realize, we haven't seen
the damage left behind by the Covenant. We've only seen how much they've advanced thanks in large part to the introduction to Forerunner relics, planets, ships, and world structures. Meridian was the first and only sign of damage we've been shown since the end of the war. We lost so many planets we'd never even seen and most of the ships I'd guess were probably decommissioned completely since the introduction of newer, better models. I mean, the Covenant-Human war ended in 2552, Halo 3. Halo 4 took place on Requiem and you can actually see the area that was Glassed by Rtas 'Vadum's carriers to stop the Flood that crash landed a CCS Cruiser in Voi. And Halo 5 took place between Kamchatka with rescuing Halsey, the Argent Moon with being caught up with Blue Team, Meridian with chasing them, Sanghelios for getting Arbiter's help, and then Genesis for the conclusion.
As for my least favorite? Not sure. I'm still learning lore bits through the books. I'll get back to you.