to descend, to come down from heaven, to send down
夅 centers on downward movement: descending, coming down from a higher place (especially heaven), or sending something down.
夅 is a less common character whose exact historical development is uncertain. It visually combines 夂 (a foot pointing downward) with a crossed-stroke bottom, which may reinforce the idea of descending.
The top 夂 looks like a foot stepping down, and the crossed bottom suggests a path or landing. Picture a foot descending from heaven to earth.
For コウ, imagine a heavenly decree coming down with a loud 'koh!' sound: koh -> コウ, as the command descends.