The Defenders Apprentice by Amelia Smith

The Defenders order is dying, but thats no surprise. Theyve been in hiding for over a hundred years, and apprentices are getting harder to find – hardly anyone can see the dragons anymore. Eppie is a successful pickpocket. She keeps her cache – and her ability to see the dragons – well hidden. One day she picks the wrong pocket, and the next thing she knows she’s been brought in to a mysterious secret order of swordsmen and swordswomen. She’s their last apprentice, their last hope. With far too little training, she sets out to help save the dragon Tiada, but if her mentor and the others fall in the battle, who will defend the dragons next time?