This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 躃 is uncertain. It visually contains 足 (foot) and 辟, but the original semantic and phonetic roles are unclear.
The foot radical 足 suggests movement, but without a clear meaning, picture a foot awkwardly stepping aside, as if limping or crawling.
For ヘキ, imagine a foot stepping on a hex key, making a sharp 'heki' sound: hex key -> ヘキ, and the foot recoils.