sword-blade ridges
鎬 centers on the raised ridge along a sword blade, a structural feature that strengthens the blade. The meaning is specific to that physical ridge.
鎬 combines 金 (metal) with 高, which likely contributes the sound コウ. The character refers to the ridge of a metal sword blade.
The left side 金 is metal, and the right side 高 suggests something raised or tall. Picture the raised metal ridge running along a sword blade: 鎬 is that sword-blade ridge.
For コウ, imagine a sword with a high ridge that makes a sharp 'koh' sound when struck: koh -> コウ, and the metal ridge rings out.