This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鍞 combines 金 (metal) with 貞, which likely acts as a phonetic component. The exact historical development and original meaning are uncertain.
Since the meaning is unclear, focus on the shape: metal 金 on the left and 貞 on the right. Think of it as a mysterious metal object whose purpose is unknown.
For コウ, imagine a metal 金 object that makes a hollow 'koh' sound when struck: koh -> コウ.