L'Arachel, Princess of Light
She is basically Ursula with better stat distribution, trading Defense for more Attack. Ivaldi's stat boost is Def +3, which may help her survive a counter from a Distant Counter melee unit.
Similar to Eirika, I would not replace Ivaldi for Blárblade as Ivaldi is pretty good.
Level 40 stats:
HP: 30/33/36
Atk: 30/33/36
Spd: 28/31/34
Def: 13/17/20
Res: 28/31/34
Total: 144-145
Default skills:
Weapon: Ivaldi
Assist: [none]
Special: Growing Light
Passive A: [none]
Passive B: Renewal
Passive C: Res Tactic 3
Ivaldi/Blárblade:
Arena offense, Arena Assault
Keen Blárwolf — Desperation — Brash Assault:
Arena offense
Keen Blárwolf — Deflect Magic:
Arena Assault
Blárblade — Close Counter — Vantage:
Arena Assault