Byleth would just be the third avatar and blue-haired swordie
Nothing wrong with that considering the Sword of the Creator and time-rewind shenanigans, IMO.
I'm curious how Byleth would difference himself from the other zoners that uses Swords and Whips... because his weapon is kind of both.
I'm imagining hitboxes that are a lot more flexible (literally), say instead of the usual "stab sword" or "whip in a straight line". Perhaps also some Martial Arts as Nemesis or Seiros does, since he bears the Crest of Flames. Say that tapping a button is a regular slash, but holding the button would have a slower, but longer-ranged whip type slash. Maybe that's just because I main the shotos, though.
You could also reference the Crest of Flames' battle ability by having the chance that landing Smash attacks can heal 3%-4%. Gimmicky, but a reference.
Because she's not only one of the central characters in the story, but she's also the closest thing to a "villain" rep for FE?
I would call her more an antagonist than a villain, the devs did an amazing job making Edelgard as morally grey as possible, even if it's not perfect.
Like I just want some validation all right? The more I see results that show Dimitri is everyone's favorite, all I can think of are the Dimitri fans who openly insuilt Edelgard fans for daring to be fans of a villain/anti-hero/anti-villain all while continuing to baby their precious Dimitri.
Sounds more like you have a problem with toxic fans of Dimitri instead of Dimitri himself as a character, and that if it was Dimitri instead, suddenly everyone will bully Edelgard fans or something. It's not gonna happen, the only salt is just from people who hate FE because Marth clones or whatever.
That's why I side with Byleth. He/she leads any of the four paths you choose and it's the most neutral, non-favored selection choice. I'm a Golden Deer boy myself and I understand that favoritism will get me nowhere. Corrin doesn't make reference to the specific path chosen in the Fates line, so I imagine Byleth fills the same gap by not advertising one route as the true route because holy Sakurai included that specific character from that specific route.
There's absolutely nothing wrong with supporting Edelgard instead, though. You do what you want and support what you want.