護心鏡 [护－镜]

Jyutping wu6 sam1 geng3
Pinyin hù xīn jìng

Definitions (Wiktionary)
  1. noun, archaic
    a special protective plate which was sewn on the front and back parts of a war garment (for protection against arrows)
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）