Eon: Dragoneye Reborn, by Alison Goodman
Eon is a candidate for the next Dragoneye, but he has a couple things working against him. First, he is a cripple, from an accident he can’t remember. And the other is that Eon is actually Eona, a girl. But females aren’t allowed to be dragoneyes, so she is forced to hide herself as Eon. A secret, that if found out, could kill her.