Since we're coming up on a new expansion full of new story, let's talk about some questions I have about HW.
1 - If no one has ever been to the bottom of the Sea of Clouds and returned, how was Foundation built? Did dragons do it all those years ago?
Foundation was likely built before the Calamity, and maybe the Calamity is what caused the Sea of Clouds to be the way it is now? If you look at, say, Western Highlands, you can tell that the area was not always frozen (they tell you this in-game too), for example.
2 - Are Nidhogg's eyes still in play? Did summoning Shinryu use up all their power, destroying them, or did someone pry them from Ilberd's corpse and walk off?
Most likely, Shinryu used the power up. I mean, c'mon, that thing is just ridiculously powerful. It takes large amounts of aether to summon normal primals, let alone something like Shinryu.
3 - The whole Warriors of Darkness thing. There was a huge buildup to something epic, and then it was suddenly over. I was left scratching my head, thinking: what was the point of all that? We didn't even get a Divine Might like trial out of it or anything. The whole story arc just seemed kind of random and pointless. Am I missing something? Was there more to it than that and I just don't get it?
You did have your Divine Might, it was just a solo duty, but a rather cool one at that. The story seemed like it ended abruptly, but I think that whole arc was more simply to remove Minfilia out of the picture and give closer to her removal all at the same time. Or at least that's the way it felt to me. *shrug* Seems like the devs/story writers wanted to trim the Scions down to make writing a little easier, so they nixed Papalymo and Minfilia so they didn't have to keep track of as many characters? That, and with the PC going to foreign nations, they really don't need all of these characters there, I suppose.
4 - The Echo. Who has it? Originally I was under the impression that all of the Scions had it (sans Moenbryda, Alphinaud, and backline people like Tataru) and it was a prerequisite to joining. After all, being immune to tempering is the main thing that lets the Scions fight primals effectively. Lately it seems like that not the case though. During one of the Warring Triad quests, Urianger can't understand those guys speaking ancient meracydian and "defers to those with the Echo for a translation." Krile definitely has it, and I assume the others do as well, but then I assumed that Urianger had it too. Fooled me apparently. Do Y'shtola, Thancred, Papalymo, and Yda (Lyse?) have the Echo?
AFAIK, the only people who currently (at the end of HW) who have it, are Krile, and the PC. During the end of the Warriors of Darkness arc when they're all teleported to meet the WoD at that circle, they're all confused/shocked as to where they are, but yet anybody who has the Echo should know exactly where they are (Krile is missing from this group at the time IIRC). If any of the other Scions have it, they sure don't show signs of having it.
As far as that being a "requirement" to join the Scions... remember that the Scions did a recruitment drive back before Baby Ifrit -- back then the Scions comprised entirely of Archons, a group of people that came from Sharlayan. They get together, and go "We gotta do something about these primals!" and so they go looking for people who have the Echo (at this point only Krile and Minfilia are known to have it). That's when they find you, the PC. Once you join.... they haven't found/needed anybody else. And besides, they do
recruit others like that group with that Roeg... I forget his name. That Roeg warrior and that Elezen conjurer. I doubt they have the Echo, but yet they were recruited?
5 - Ascians. Seriously, WTF?
Mebbe that'll be explained more in SB? lol.