Ah, sanctification is also a thing in the Prophecy. While a blessing is like a "lightweight" invocation of the protection of a deity on that particular item - one that may cause discomfort for those directly related to other deities or even hurt them somewhat - and is usually very temporary, sanctification is sort of the heavier version of a blessing. Not only does it usually take a lot longer to sanctify something than to bless it, and it requires much more elaborate rituals to make it so, but sanctification is often permanent or near-permanent, and can only be removed through desecration of the sanctified item or area. The effect of sanctification is also much stronger than that of a blessing, though it won't affect as wide a variety of things (it can't disrupt energy, for instance, and won't particularly affect vampires beyond making them slightly uncomfortable), but will outright prevent other deities from acting against that which is sanctified at all. Places of worship are often sanctified, which also why Rilon needed Thaler to steal the White Rose for him, since he is literally incapable of acting within the Cathedral of Reina himself. Demonspawn are also somewhat affected by sanctification, as long as it is not in Himyth's name, since they possess the blood of a deity; for them, entering a sanctified area is not only nauseating and slightly painful, but weakens their powers and hinders their movement.
Objects that contain the energy of deities are not actually referred to as blessed in the Prophecy. Rather, an object containing the energy of a god is "divine", and an object with the energy of a demon lord is (you guessed it) "infernal". The term "cursed" is indeed used about harmful enchantments, usually caused by mortal magic, and "damned" is (as one might naturally assume) the opposite of "blessed", and can also be caused by gods and demon lords alike. In other words, it is that a deity decides to invoke their disapproval of a thing, which ironically [I]also[/I] makes it difficult for other deities to affect the damned object. The main difference is that, whereas a blessed object will be under implied protection of a deity, a damned object will be rendered significantly more fragile and vulnerable.
It was actually my original idea to name the demon lords "devils", but it didn't end up that way because the term "devil" came to mean something else; a distinction not usually made by mortals, but is considered moderately significant in the Underworld. "Demon", to them, is basically the vast majority of demons, which is those created from dead spirits. "Devils" are the demons created by Ismyel in the Dawn of Time, the first of their kind and those whose definition of "evil" is derived directly from that of Ismyel, and as such represent the very worst of their kind. So yeah, demonic deities ended up being demon lords.

And yeah, the post is much better now. Sensing the nature of a spell, though? They can to an extent, yes... They can sense a lot about a spell just by how it feels (though comprehension of what they sense may not be instant, mind you; the ability to analyze what one senses, and doing so quickly, is something that needs to be learned), and in this case a sniffer would certainly be able to tell that it was a mind-affecting spell being cast... but not whether it was harmful or not. The energy-signature of the spell quite simply doesn't reflect that.