The Grimoire of Pope Honorius is so named because it purports to be a short collection of prayers and invocations with rituals designed to call forth demons from Hell, allowing a holy conjurer to enslave them to their own designs.
The lengthy invocations call upon various names ascribed to YH.
While it is not certain that Honorius is its Author (and it may take its name from the "Sworn Book of Honorius" instead) it is well known within the occult world as a Grimoire worth pursuing nonetheless.
The Grimoire of Pope Honorius is so named because it purports to be a short collection of prayers and invocations with rituals designed to call forth demons from Hell, allowing a holy conjurer to enslave them to their own designs