Alle Kunst ist der Freude gewidmet

Ack, not familiar enough with Magvel yet to contribute much. However, I don't think you need to worry about setting too much store by "how things were" on Earth. Supernatural elements aside, FE universes are more heavily informed by modern sensibilities than we might think at first glance. If Eirika was able to lead an army without question for at least a good part of the story, I don't think she'd be treated as just another piece of property right afterwards. Buuuut again, I've only played through the game once so I'm probably not the best authority.

Now, with Uther... there was a bit in FE6 that never really got cleared up in FE7, where Hector is apparently the half-brother of the marquess of... Worde, I want to say? He was never mentioned in FE7, which kind of makes me think that there's more to their family dynamic than we see. It's certainly possible that Uther had kids, but then why would Lilina become marchioness after the war if they were still around? Did they get killed in the rebellion? Speaking of which, considering how many revolution plots have been cooked up against Ostia, it's certainly possible that Uther and his parents didn't just die of natural causes.

Also, I read on Serenes Forest that Lilina and Thito were originally supposed to be cousins, so maybe she was originally Uther's daughter? It wouldn't work given what we know now, but it's at least something they considered.