"Comely" is an old word roughly meaning "pleasant", "good", "handsome" etc. I would interpret "all comely" to mean good/pleasant in every possible way (good looking, kind, generous etc.). Once again, this isn't exactly current English; so I suspect you found this phrase, in a rather old book, possibly referencing the Biblical character of Joseph-son-of-Jacob.

'Comely' is an old fashioned word used in the Bible and Shakespeare to mean pleasing and wholesome in appearance or attractive. Comely behaviour is described as modest, suitable or seemly