Someone who will wait.
He waited for the food road to be cut off, for Zhao Jun to be hungry, and for Zhao Kuo to make a mistake. He squatted on the edge of the valley in Changping for forty-six days, waiting for 400,000 people to change from having food to having no food, from being organized to being defeated, and from being alive to being surrendered. Forty-six days later, he stood up and made that decision, and then spent the remaining half of his life waiting for the echo of that decision, waiting for it to slowly grow colder, grayer, and lighter in his bones, until in the end it no longer needed to be remembered.
The moving part is not those hard-core war deductions, not the semaphore, the deduction platform, and the calculation of food routes - but the days when he sat alone in the library after all the battles were fought. He sat in his residence in Xianyang all winter, watching the pomegranate trees in the yard lose their leaves, waiting for the people in the court to decide where he should go. He sat there without writing, asking for help, or explaining. He did not argue when Fan Ju oppressed him in the court, he did not argue when the King of Qin dismissed him from military power, he did not complain when he was demoted to the rank of soldier, he did not have any unnecessary words when he went to Yinmi, Du You, or to pick up the dagger. He'd known those things were coming, he'd just waited for them to come.
This kind of waiting is more difficult than fighting.