... Harry's risen from the dead.
Well... from the almost-dead.
But yeah, Vadderung indicates it's "special," and "not as common as you'd think" -- it makes him interesting, worth paying attention to, for beings who previously haven't thought him to be so.
He's the Winter Knight.
Honestly, this is nothing much. I think Bob likened the Knights to Kleenex -- useful for a certain kind of mess, but fundamentally disposable, and not worth much attention or effort, nor any regret for their loss.
Mab's long labors keeping Harry alive into & through Ghost Story would appear to be exceptional; or maybe Bob was wrong...?
He hang's with Archangels.
Yeah, this one seems like an extreme case of "exceptionality."
Uriel himself mentions that his degree of interaction with Harry is highly unusual. "I can hardly remember the last time I spent this much time with one particular mortal" (n.b. not
I can't remember (which would imply
NEVER... because...
Uriel ffs!)). So, a turn of phrase, a vernacular meaning "it has been a
very long time."
And he knows a thing who knows a thing.
Honestly, this one is just Harry... It's the trope of the "hard boiled PI."