The ascription to Pietro d'Abano is rejected on chronological grounds, which removes an author without supplying one. The text first appears in print in 1559 appended to the pseudo-Agrippan Fourth Book, and no manuscript witness earlier than the sixteenth century has been identified for it. Its angelic hours and weekday conjurations resemble material circulating in fifteenth-century ritual manuscripts, but resemblance is not descent.
What would resolve this A dated manuscript of the text or of a recognisable portion of it from before 1559, or a securely dated source that the printed text can be shown to be copying. Collation of the Heptameron against the surviving fifteenth-century angel magic manuscripts, done systematically rather than by impression, would establish whether it is compiled from them.
OpenHistory of the book and early printing, Latin palaeography, and the study of late medieval ritual magic manuscriptsOwen Davies, Grimoires: A History of Magic Books