驽钝

dāo qiào zài bǎo hù dāo de fēng lì shí zì jǐ yě mǎn zú yú tā de nú dùn

刀鞘在保护刀的锋利时，自己也满足于它的驽钝。

The scabbard content to be dull when it protects the keenness of the sword.