The Mask of Aribella by Anna Hoghton
Aribella lives in Venice, the daughter of an impoverished lace-maker. But she has a deadly secret: when angered, sparks shoot from her fingertips. Unable to keep her power hidden, she flees - but when dark spectres rise from the lagoon, the fire in her hands saves her life.
A stranger witnesses the attack - and through him, Aribella leaves her old life behind and discovers the world of the Cannovacci, magical warriors sworn to defeat the strange spectres menacing the city ...