This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
縨 combines 糸 (thread) with 晃 (bright, shimmering). The exact historical development is uncertain, but it likely relates to a shimmering fabric or curtain.
The left side 糸 suggests thread or fabric, and the right side 晃 suggests brightness. Picture a shimmering curtain made of bright threads, though its exact meaning is unclear.
For コウ, imagine a shimmering curtain glowing with a bright 光 (こう, light): 光 -> コウ, and the fabric shines.