quiver (case for arrows)
櫜 centers on a container for arrows: a quiver or case used to hold and protect arrows.
櫜 combines 木 (wood) with a phonetic component that also suggests a container or wrapping. The exact historical development is uncertain, but it likely originally depicted a wooden case or box.
The top part looks like a lid or cover, the middle 咎 suggests something stored, and the bottom 木 indicates wood. Imagine a wooden box with a lid used to store arrows: a quiver.
For コウ, picture a coat (コート) hanging next to the quiver: coat -> コウ, and the quiver holds arrows like a coat holds a person.