This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
銺 combines 金 (metal) with 壯, which likely contributes sound. The exact historical development is uncertain.
The top 壯 suggests strength or robustness, and the bottom 金 is metal. Picture a strong metal object, but its exact meaning is unclear.
For ソウ, imagine a strong metal saw (ソウ) cutting through the 壯 top: saw -> ソウ.
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