Mizu shika Denai Shingu [Cup] wo Sazukatta Boku wa, Fumou no Ryouchi de Suki ni Ikiru koto ni Shimashita

Sian Burdrey was born into a big royal family and was promised his life would be a smooth sailing. However, after receiving a sacred "cup" that can only produce water at his coming-of-age ceremony, he was thought to be worthless, and got banished from the family to a frontier desert as its lord. Even though Sian hit rock bottom because he lost both his beautiful fiancée and his privilege as an heir to the throne, upon hearing the people suffering, he decides to get back on his feet and to stand up for them. Sian uses the "cup," and tries hard to revive the land. Surprisingly, it seems this "cup" can produce more than just water?! Here starts the story of a boy who was once called even worthless saves the world! Source: Alpha Manga