Sick Bones Seek the World

The direct descendants of the family are all strong men who are supreme in force, but they are killing each other due to internal struggles for power. Being in frail health, I, as the only member of the collateral family, was forced to replace the illegitimate son who tragically died of the family head and take over the mess. When everyone was waiting to see me die of illness or surrender, I just shook my paper fan and condensed a plate of loose sand into the strongest force. In the end, when the enemy came to the city, the direct lineage was shocked to realize that the most powerful sword in the world was actually an invisible chess game created by my wisdom.