Ursula K. Le Guin

When young Gavir's sister is brutally killed, he escapes from slavery and sets out to explore the world and his own psychic abilities.

When a young man in the Uplands blinds himself rather than use his gift of "unmaking"--a violent talent shared by members of his family--he upsets the precarious balance of power among rival, feuding families, each of which has a strange and deadly talent of its own.