leather arm-band
韝 centers on a leather arm-band, a protective or decorative band worn on the arm, typically made of leather.
韝 combines 韋 (leather) with 冓, which likely contributes a phonetic element. The character specifically denotes a leather arm-band.
The left side 韋 means leather, and the right side 冓 looks like a band wrapped around something. Picture a sturdy leather band strapped around an arm.
For コウ, imagine a leather arm-band worn by a coach (コウチ) during practice: coach -> コウ, and the band is made of tough leather.