Read about the Paranet Papers here: http://www.evilhat.com/home/state-of-the-hat-2012-nov/ It's not going to include any kind of Fate Core update in it, though.

A Dresden Files Fate Core conversion would be of minimal use because there's so much legacy stuff in there that'll "corrupt" the mix, if that makes sense.

The specific point is important.

So If the headaches are due to the parasite, and the parasite is from Harry's encounter with HHWB, then something later must have trigered it's... rambunciousness.

Or there is another explenation that doesn't involve the HHWB encounter.

How long has the White Council had the Blackstaff
Look for Celtic Lore around 1065 ad.

Now we have another search term to find the actual lore behind "The Case of the Stolen Walking Stick"

I am utterly convinced, in real world folklore, that people have utterly misinterpreted the phrase "cold iron".

"Cold iron burns faeries" is the basic folklore.

People have thus tried to figure out what "cold iron" means -- is it cold-worked iron, does it include steel, must it be meteoric iron, etc.

I think people are overthinking.

Remember, in folklore, one can thwart the faeries by turning your clothes inside-out. So, "cold iron" is just a reversal. That is, I read it so:

"Cold (room-temperature) iron burns faeries (as if it were red-hot)."

In the Dresdenverse, it's way more expanded than that, but I think starting from the idea that all iron and steel are poison to the fae is a good way to go.