ㄅㄠˇㄉㄠㄨㄟˋㄌㄠˇbǎodāo‑wèilǎo

宝刀未老
  1. 比喻年紀功夫技能仍然精湛 老爺爺依舊力道十足真是寶刀未老」。

treasure knife does not age (idiom)​; old but still vigorous