The biggest problem with Lyse is that it feels like the writers didn't fully understand what kind of character they wanted to make.

Most of her dialogue in SB is her crying about how she's supposed to charge into the enemy, supposed to take action and be the main character but she's always being outshined by the WoL.
Yet this doesn't lead anywhere, it feels like at some point there should have been a scene where Lyse charges into enemy territory blindly, a bunch of allied troops go after her and she ends up causing a bunch of casualties. Hell I was surprised it was Alisaie who got all gung-ho during the Lakshmi scene.

As it is now Lyse just whines and cries until she gets what she wants, she's never forced to mature and even at the very end she's mad that she wasn't the one who got to kill Zenos.