As a pretty experienced Fire Emblem fan, this is certainly enjoyable but I have a couple of pain points.
First, Tsume's training arc is kinda rough. She's already wildly under-leveled compared to Victor and Vania but then the next couple of maps is mostly enemies she lacks WTA on and mages that render her unusable so it's just an absolute pain to get her ramped up. I'd get it if she were a Villager-style archetype who starts weak and is annoying to train but had high growths to reward you but that doesn't seem to be the case (or if it is, my blank level up was incredibly unfortunate).
This is compounded by my second point, Vania's ability. Don't get me wrong, it's good, but the fact she completely takes over combat means you can't even use it to help train up someone like Tsume because Vania will just snipe the kill. It's also kind of anti-synergistic with Victor's ability as there will be times I want him to enemy phase mages and I'll have Vania next to him to him to boost his Res, but then her ability procs, she doesn't double and the mage is still alive.
And in what I assume is a bug, I somehow declined Victor's Mage reclass which is a bit of a run killer. Thankfully I stagger saves and could go back to before that scene.