"Miss Greythorne, a powerful Old One who also happens to wield a sword cane."

For J. L. Bell, it's all about the Walker's love interest. 

For me, it's all about this sword cane business.  And the fact that they've dropped "all the Arthurian stuff".

I'd assume that means they won't be making movies of the other books.  If you take Arthur out of The Grey King, there wouldn't be a whole lot left.