This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 銽 is uncertain. It visually contains 金 (metal) on the left and a right side combining 口 and 氏, but the original component relationships are unclear.
Since the meaning is unclear, focus on the shape: metal 金 beside a mouth 口 over a clan 氏. Picture a metal clan emblem with a mouth-like opening.
For カツ, imagine a metal cutter that goes 'katsu!' as it slices: katsu -> カツ, and the metal 金 side hints at the tool.