While I think that the story has an intriguing premise with good potential, the idea of anything humanoid crawling headfirst down a vertical wall is very dubious. Another point: “sheathe” is a verb: “sheath” is the noun.
As for crawling headfirst downwards, that’s a direct copy of how Mr. Hyde climbs in the original tale of Dr. Jekyll and Mr. Hyde, so take it up with the late Mr. Robert Louis Stevenson. :)
shadowlight
C. Augusto Valdés
August Rode
Raymond Finn
August Rode