All he could do was to take small strips of heat-treated metal and rub them lightly against different parts of the sword to judge its hardness by the sound.
但是扣鳴刀不能做破壞性測試，只能用經過不同程度熱處理的小金屬片，藉著輕微的摩擦聲來判斷刀身各部分的硬度。