Close counter W Cecilia

Unless she's running Vengeful Fighter, I wouldn't recommend it. Her defense is good, but not amazing when compared to the damage hard hitters can do to her. Unless you put a def refine on the dagger and give her some buffs in that category, I feel that it would fall flat on its face since she's outsped by most of the hard hitting units.
But hey, do it if you want. That's just my take on it. If you do, here's what I'd run on her.

Rouge Dagger (def)
Swap
Bonfire
Close Counter
Vengeful Fighter
Even/Odd Def Wave
Atk/Def Bond