This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鑅 is a phono-semantic compound with 金 (metal) on the left and 榮 (glory, flourish) on the right, likely contributing the sound コウ. The exact historical development is uncertain.
With metal 金 and the flourishing 榮, imagine a metal object that shines brightly, but its exact meaning is unclear.
For コウ, picture a metal 金 object glowing with a bright コウ (光, light) as it flourishes 榮: 光 -> コウ.