ornament over the horse's head
鎫 refers to a decorative ornament placed on a horse's head, likely a metal fitting or crest used for adornment.
鎫 combines the metal radical 金 with a phonetic component that is not clearly identifiable in modern form. The exact historical development is uncertain, but it likely originated as a character for a metal ornament.
The left side 金 (metal) tells you it's made of metal. The right side looks like a fancy headpiece with a top stroke and a box-like base, like a decorative crest placed on a horse's head.
For バン, imagine a horse wearing a shiny metal ornament, and the horse's name is Ban: Ban -> バン, and the ornament is on Ban's head.
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