Maryoku Zero no Ochikobore, Jusatsu no Youtou ni Erabareru.

Synopsis

In a world where magic is commonplace, Chrom, the son of nobility, possesses no magical power whatsoever. Though unable to wield magic, he trained in swordsmanship, striving to be useful to the world. Yet his own father and brother branded him useless and banished him. His exile destination was a forest teeming with monsters. As Chrom lay crushed by despair, a monster appeared before him. Just as he resigned himself to certain defeat, the cursed sword discarded alongside him spoke to Chrom... (Source: Coamix, translated)