... I suspect the Spear is especially potent in Harry’s hands as a Starborn, Harry has been unusually resistant to prophecy, entropy curses and death curses, all things designed to shape destiny but as a Starborn it gives Harry a partial shield to such things ...
That's an interesting theory, that being a Starborn gives him an extra "leg up" on the whole "destiny" schtick; do we have direct canon or WoJ on this point?
I don't think "death curses" are evidence, here: I think Harry just found a loophole in Cassius' curse (and he had to
become a ghost to do it! So, it was a pretty-extreme reach, to get to that loophole; Odin himself suggests it's a pretty-rare occurence ... )
Also, I think the only "entropy curses" Harry dealt with were Papa Raith's, which seem to be Outsider-powered (so a Starborn already has the wherewithal to deal with those, without invoking further "destiny" powers).
The "Barabbus Curse" (an inescapable death, which is a pretty damned "destiny" sorta thing!) from Death Masks was Denarian, not Outsider ... but it was I think Shiro who broke that, not Dresden (and we know that the KotC's have their own freakin' "Destiny" powers!).
Early on, Marcone saves Harry from Capiorcorpus & the ghoul; Gard warns Marcone that it was Harry's "destiny" to die there; again, not Dresden's doing (I actually suspect Uriel's hand, here).