Enchantress by James Maxwell
Ella and her brother Miro are orphans, their parents killed long ago in the ongoing struggle against the mad Emperor.
While Miro yearns to become a soldier - and shows promise - Ella's own dream is considered impossible. Ella wants to study at the elite Academy of Enchanters and design magical weapons for her brother to take into battle.
Yet Ella tries anyway. And when the Emperor's all-conquering army approaches, Ella's journey will leave her holding the fate of her homeland in her hands.