I wonder if she looked over the documents gathered by the revolutionaries and remnants of the Three Heroes Sect?
….Nah. Witch is only concerned with knowledge about using others; she wouldn’t think to make such calculations herself.
She probably intended to lure Raphtalia into a trap while calling it a 1 vs 1 battle this time as well.
Or rather, she intended to brainwash Raphtalia using the dagger.
She would win with if she got a single hit in, so even if her ability was inferior, she could end it with one shot.