EvilDMMk3

It seems like you might be going at this backwards. Don't ask can I, ask should I. I can see plenty of ideas that might work with this premise, but the better way to think is "what story am I trying to tell that this helps". For example if you want a story where someone has found a way to ascend Mayor of Sunnyville style then you may well want to tone them down somewhat. Likewise if you want a World War C ploy where the humans fight the Old Ones. But in most games I think it would harm the tone. TLDR, maybe. Why?

In what way?

So, I asume I am not the first person to notice that Occult's description implies it is worthless. To whit: "This skill does not apply to spells, books, and the magic of the Cthulhu Mythos, although occult ideas are often adopted by worshipers of the Great Old Ones." So, it is a skill that lets you identify anything except anything that might be useful. That, well it seems wierd if only because it works as a perfect Mythos detector. I mean, think about it, you show an Occult expert 3 books, The Practices of The Dark One, The Hammer of Witches and The Book of Going Forth Around Lunchtime. The expert idenfities the latter two, so you know the first one is a Mythos text. Would it be so game breaking to change it to read the following: "This skill cannot differentiate between spells, books, and the magic of the Cthulhu Mythos and more mundane Occult beliefs. In addition information is likely to be obscure (prehaps requiring a Hard roll) and vauge, such as idenfiting The Necronomicon as simply 'An occult text reputedly translated from an Arabic text by Occultist John Dee.' and (as an Extreme roll) Nyarlathotep as 'an obscure Ancient Egyptian firgure, possibly a deity or a Pharoh, records are unclear'."