reed
簆 refers to a reed, specifically the comb-like tool used in weaving to separate warp threads and beat the weft into place.
簆 combines 竹 (bamboo) with 寇, which likely provides the sound. The character is used for a reed made of bamboo, consistent with the bamboo radical.
The bamboo top 竹 hints at a tool made of bamboo. The bottom part 寇 looks like a complex arrangement of threads being combed by a reed during weaving.
For コウ, imagine a weaver using the reed to create a coat (コート) of fabric: coat -> コウ, and the reed helps make the coat.