Part 1: Sorey becomes the Shepard. Alisha is squire. You start sheparding and there's some background story about Hyland and its internal corruption. Standard story fare, nothing off about this part except maybe Lunarre and his people eating being dropped entirely and not picked up on again until way later. Same with Edna and Eizen. And Zaveid's intro, now that you mention Eizen... none of these plot threads are even hinted at until almost the very end of the game.
Part 2: Alisha leaves, Rose suddenly becomes a different character entirely and takes her place. Dezel comes with her for ominous reasons. You can tell the story's structure is waning when the game throws about seven sidequests at you at once, all of which tread a thin line between unrelated story vignette and integral to the main plot of the story, the iris gem quests being a good example. Or finding a new hideout for the Scattered Bones - lol woops, nevermind, the hideout is no good and they're going to go, um... back to where they were, I guess? None of the sidequests feel fleshed out enough. There's a lot of lead-ins to things, with the constant hints to Dezel's past and the young Emperor of Rolance, and the pacing of the game changes. The lead-ins are fine here, but fall apart in the last third, so the game is setting you up for disappointment in this regard. The main story is still good here, though. The elemental trials are really nice and the character interaction reaches its height here.
Part 3: Here's where everything falls apart, starting with Dezel's death and flashback scene. This is the game's finale, where we expect to see the resolution to the plot threads hinted at earlier, but they are all - and I mean literally all of them - rushed to the point where they feel inconsequential. Dezel's flashback doesn't really make any sense, who is that other guy, how does he know Zavied, how does Zaveid know Eizen, who even is Zaveid and how did he get that gun and if it's so special why did he waste it fighting Sorey for NO REASON, why is Zaveid wearing Dezel's hat ("let me fill the Dezel shaped hole in your party" - LOL), why is Eizen a random sidequest you get from sleeping at an inn and how come we don't see his seraphim form, who is loli girl and why is she the only dark seraphim, what exactly did Heldalf and her do in between being cursed and becoming an evil lion man, the list goes on. Then there's every villain that didn't get their chance to shine getting thrown at you in a gauntlet of "villains we forgot about" boss fights with very little exposition or resolution. Oh and by the way, did you know Mikleo was a human baby and his uncle was the previous shepard? Because the game does a terrible job of telling you that.
