This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 翈 is uncertain. It visually combines 甲 and 羽, but the original semantic or phonetic role of these components is unclear.
With 甲 (armor) and 羽 (feathers), imagine a warrior's helmet adorned with feathers, but the true meaning is unknown.
For コウ, picture a coat of armor (甲) with feathers (羽) that makes a loud 'koh!' sound when struck: koh -> コウ.