The Two Princesses of Bamarre by Gail Carson Levine
Addie, the 12-year-old Princess of the kingdom of Bamarre, is a sweet but cowardly girl. She comes by it honestly – her father, the king, is also a coward. Addie’s sister Meryl, however, is adventurous and courageous and she wants to save their kingdom from evil magical beasts and a plague they call the Grey Death. Addie adores and admires Meryl and she knows she’ll never be brave like her sister.
When Meryl gets sick, Addie is desperate to save her but,