reins, connection
覊 centers on the idea of binding or linking: reins that control a horse, and by extension any connection that ties things together.
覊 combines 覀 (a variant of 西, possibly representing a cover or net) with 䩻 (leather and horse), suggesting leather straps or reins used to control a horse. The exact historical development is uncertain.
The top 覀 looks like a cover or net, and the bottom 䩻 contains 革 (leather) and 馬 (horse). Picture leather reins draped over a horse's head, connecting rider to animal.
For キ, imagine a key ring connecting your keys: key -> キ, and the reins are the connection that keeps everything together.