+Attack Sanaki

Well...I suppose i you have Eirika or Ephraim buffing her to hell, the R tomebraker and huge attack makes up for the inability to double most units...though ordinarily her default best build is Triangle Adept and the red Raven tome with Swordbreaker. It's probably the only really useful way to build her beyond what you have already. Though her defense penalty means that if you fight a brave bow Lyn with Hone Cavalry, she'll just barely kill Sanaki (Lilina is generally better for this because of the extra defense she has over Sanaki)

She works best with a Raven tome. TA and Swordbreaker makes her kill if not the entire green and colorless cast

I would really also suggest to get TA / raventome it's such an incredible build and also it changes a bit from the classic blade mage.

But if you really really want to build her that way I guess she'll still be able to burst pretty hard. Maybe take swordbreaker instead of red tomebreaker as there is very few red mages in the meta.

Raurraven+ with TA , sword breaker and hone attack is an amaizing sanaki.
People seem to underestimate her but I think she is really good.
My sanaki (attack plus adn speed minus) can one shot hector with hone attack buff and other fearsome green and red units.
The only one she won't be able to kill would be xander, ike, ryoma. For these you can let your blue units to take care of them.
Overall I have been using her for about 3-4 months and I already got her to have 9999 sps (the max sp that you can earn for a character with 3000 hero merits). As you can see sanaki is a very valuable unit to me and she is in my number one team.
Conclusion: many people underestimate her and think she is really bad, but i don't think that is true.

I also made a big analysis on sanaki at the time when this website was at its early days. I am not sure if I can keep track of my posts though ...