This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 銎 is uncertain. It visually combines 巩 and 金, but the original semantic and phonetic roles are unclear.
Since the meaning is unclear, focus on the shape: 巩 over 金. Picture a metal (金) tool with a sturdy (巩) handle, but remember this is just a visual mnemonic, not a real meaning.
For キョウ, imagine a strong (巩) metal (金) key you (キョウ) use to open a mysterious box. The sound 'kyou' from 'key you' cues キョウ.
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