Katarina still has the Shadowgift skill in this timeline, like in Awakening's DLC...
- And Gharnef knew about it, which is why he killed her parents and had her raised as a Tyke Bomb by Eremiah. The downloadable chapters heavily Katarina was specifically "selected" by Gharnef and Eremiah for recruitment into the assassins, and the natural ability to use dark magic sounds like a very good reason for this. Furthermore, this creates Fridge Brilliance, as a very similar situation happened in Awakening with Validar killing Aversa's family and manipulating her into becoming his servant, due to her having the valuable Shadowgift. It makes sense it wouldn't show in-game, as the only real dark tomes in New Mystery are unobtainable so Katarina wouldn't have a chance to use them anyway. (And of course the main one is Imhullu, which no-one in their right mind would attempt to use anyway.)
Mila and Duma are members of the Dragonkin.
- Duma's appearence resembles a dragon, and Duma was capable of providing a sword that the wielder could use to deal with both himself and Mila, and said sword happened to be called The Falchion. And FE (as well as Tear Ring Saga) has several examples of Dragons being worshiped by humans.
- "Duma's appearence resembles a dragon..." No it doesn't. Duma's appearance is a cyclopean pile of muck which can extend Combat Tentacles.
Athena is from Valm.
- Athena mentions that she comes from another continent, it's probably a part of Valm. It's close enough that the pegasus knights could fly there.