Rise of the Outcast Prince

The royal family holds a sword art called the Overlord Blade, and in eighteen generations not one of them has managed to master it. Darius is the fourth prince, but his mother was a palace maid, so the family treats him as lowborn, does not count him among its princes, and forbids him to learn the Overlord Blade. He is also the one the heavens chose, and after a single look at the technique he has its first move, which he keeps to himself. The chief councillor of a rival kingdom, a man who has learned every fighting technique in the world, arrives at the palace to take the Overlord Blade for himself. The palace falls into chaos. Darius fights back to protect his mother and goes up against the councillor.