Reddd maggeee

Love that sanaki <33

I would use tharja. Your IVs are basically perfect and she can nuke really well. I would recommend putting her on a team with an Eirika or a PA!Azura.

I would do Arvis or Tharja.

I'd personally say Sanaki, especially if you give one of the Henries' Raven tomes to her. She already has Triangle Adept, and her defenses aren't deplorable. She can definitely hit hard, and I don't think there are many greens that can survive her.

Looking over those IVs, I'd vote for Sanaki. She's a great unit and those IVs play to her strengths. Some things to note...

o +RES Sanaki could tank Reinhardt as a Red before it was cool (Sigurd is such a poser). This is even easier now that seals can be upgraded!
o Highest ranged attack in the game gives her great OHKO potential meaning Deflect Magic isn't as much of a problem for her.
o Her immense resistance and attack give her insane burst damage with Iceberg/Glacies.
o Her legendary tome doesn't have the best secondary effect but it still has high might and good arena scoring.
o If you run her with her default Triangle Adept, she'll be great against Greens of course... But if you run with a different A slot she becomes an incredible magical duelist capable of outfighting even some Blue casters.
o Speed doesn't really matter for her so -SPD is perfect. Just give her a breaker or QR2 in the B slot.

I have a +RES -HP Sanaki and she's one of my favorite heroes.

Try this build:

Cymbeline
Rally Attack
Iceberg
Triangle Adept 3
Swordbreaker 3
Hone Speed 3
Fortify Def/Res

And have her ally support be a bladetome user like Nino or Linde.

Her primary goal will be to take out red lords and green units while supporting blade tome users.

You can substitute her legendary tome for a raven tome to become an anti-colorless unit, but it might be more difficult to one-shot Hector unless you give her a +atk seal and also compromise some support utility with blade tome users.