It means 'stupid' in Scots so... probably just a joke by the author? Or maybe they were reaching for some similar words and missed - like 'drookit' (soaking wet), 'gloweret' (ominous sky), 'gloamin' (twilight), 'glaupit' (slimy, muddy), 'glamsy' (sky a mix of bright and dark)
There's a dictionary here https://dsl.ac.uk/ but glaekit is a common enough word in normal conversation in scotland, most people here would know what it means.