As far as I know, the old ugly bitch hasn't had her comeuppance yet. I'm not up to date with the latest of the novels, though, so, take that with a grain of salt. Her methods of pushing Ellie to her limits are good, but unfortunately, she's been shackled by a deep resentment for the main family (I hope the manga/novels expound on this in the future - it'd be interesting to see the background of why she has so much bittterness). Ellie is just shy and doesn't like to stand out (as somebody mentioned before) and Lita is pretty much one of those natural born leaders but she's also had to work extremely hard to develop herself. Ellie wants to be strong, but she doesn't want to be stronger than Lita. She wants to stand by Lita's side, but she doesn't want to be stronger. I think she'd even be fine with being weaker than Lita, but definitely doesn't want to be stronger. Contrary to what somebody said earlier, Lita is actually good for Ellie. Ellie's not a leader and it's hard for her to think for herself. She can do it, but it's not what she naturally is bent to do. She wants to follow a strong person (Lita). She wants to just do what somebody tells her to do. Lita is a person who can figure things out and wants to protect people and has a fairly charismatic personality. Even though she's not the Duke's natural daughter, she has it inside of her to lead and protect. Ellie started focusing more after she met Lita and had a purpose in life. When she finally saw that Lita didn't seem to have any mana, she was pretty much heartbroken and saw her dream of standing by Lita and protecting what's important to them die. She was basically just going through the motions again. And as you'll see after this fight, She'll get back her spark and motivation after this. (not gonna give any details, but it's a good story arc). Anyway, I've rambled on long enough. Sorry for that, but I really like this series a lot.
tl;dr Melida is good for Elise and the old hag needs to lose the bitterness.
