Knocking unconscious is a good choice, because the process from coma to awakening, then breaking free from captivity, usually takes well over forty-five minutes, and can even last from a few hours to a day.
However, in a battle of evenly matched forces, it's often hard to control this degree, and if one is not careful, they might end up dragging themselves into it.
Therefore, Fang Heng uses 'as much as possible', rather than a must.
During the moment of sign language communication, the two Great Swordsmen have already approached, they have not noticed anything unusual around them, and continue talking to themselves. Fang Hong listens quietly to Miss Tata's translation, the two are discussing trivial matters, occasionally revealing some useful keywords.
