Yeah, keeping her seems storywise, but damn her combat skills are so underwhelming. I mean Cora has blizzard, Cora has a damn lightning with 450 damage and 5 sec. And what does Scarlet possess? Silence and sleep. You know, i'd get over silence, but we get a staff of silence the very mission we get to play Scarlet, which is...well, renders her first ability kinda useless. I mean it has superior duration, but I sacrificed Cora for her. Sleep, well sleep is sleep. Her ultimate is strong though, but that's pretty much her only advantage.
Cora is a high ranking member of the Imperial Army, so she must have received better training than Scarlet. She was trained to fight at the frontlines, while Scarlet was a noble.