So far I have been running damage calcs on +Atk/-Res Cordelia with:
Brave Lance +
Reposition
Galeforce/Moonbow (Moonbow for OHKO on Nowi)
Death Blow 3
Lancebreaker 3
and this setup is able to OHKO all red blue and grey units (with or without fury) barring Nowi unless you are able to proc Moonbow. (notables being Effie with wary fighter, Takumi, Lucina, Epharim)
What passive should I run in the C slot, and who would be some good team mates for her? Also who doesn't she OHKO?
https://rocketmo.github.io/feh-damage-calc/ can you test a bit yourself what you OHKO and what survive. Still bulky units with only ~25 spd is not your problem because cordelia is fast with 30 spd enemy need atleast 35 spd or debuffs to double you.
c slot what you like buffs/ debuffs example Threaten Def 3 is good -5 def for more 10 dmg abuse.
I already god a +Atk/-Res Cordelia, so Personally going with this build:
Brave Lance+, Darting Blow, Seal Def, Theaten Spd, Reposition, and currently stuck between Galeforce or Moonbow.
As for a partner, i found out that Caeda works best as she grants Cordelia +6 Def/Res, covering up one of her only weaknesses (besides the bow), while also having access to Rally Speed. Shes a fantastic buffer for a 2-flier duo.
Still need to 5*, but here it is. Even as she is, shes a monster when paired with Caeda. Can;t wait to get her to 5*
As a Brave weapon user, I personally would think Deathblow would grant you more in terms of power rather than speed but that's just me, your Cordelia seems fine and I also have one as well with the same IV spread but with a different build planned, it's going to be trickier though because I got her at a 5*, which means I gain less SP in general.
Pokemon GO
Fire Emblem Heroes
Fate Grand Order
Dragonball Legends
Dragalia Lost
IV Calc
Heroes