Azura's defenses are comparable with Ninian's, and her offensive capabilities are MUCH higher because of the Sapphire Lance. Her speed is high enough that she'll often double a lot of units too, so I slapped Astra on her and she can just wreck things on her own. I do want to give her something more defensive though, since Astra assumes she's taking some hits too to charge it up at any reliable pace-- or maybe Killer Lance+ for the faster charge, but that'll be a bitch to get the SP for. On the other hand, giving her Escape Route like Ninian could be useful too, just for the added utility.
The only reason I'm really using Ninian at all is because the Arena demands her over Azura for ranking purposes, but after this rotation I'll likely drop her.
Additional thought: Killer/Brave weapon + Sacred Cowl/Escutcheon would practically give constant defensive uptime for a squishier unit.
I really, REALLY wish this game were less stingy with the grindables. There's a lot of room for exploration with team building and inherits, but if you can't reliably farm crystals, SP, and ESPECIALLY those damned feathers, then it's just a huge, grindy slog (read: not fun). I want to feel like I'm making some kind of progress in the game, and to be very honest, the benefits of ranking up units and inherits, while nice, are situational and the benefits are marginal. It doesn't feel like my effort earned much reward (using PAD as a reference point, where high-effort evolutions feel much more rewarding by giving a much stronger unit who is noticeably better than its previous form, or changes how the character is played for that added variety).
I really want to like this game and in a sense I do because I keep playing it (but it's more because it's always in my pocket and I'm pretty much burned out on PAD for the rest of my life outside of the events that interest me), but there's so much room for improvement and so much potential this kind of game could have that it doesn't. It really just makes me want to play the actual Fire Emblem games instead of it, which may be part of the point-- the push in interest makes me want to buy the games instead.