Lash
Lash's death is indeed a shame, but I think it has to be done or the story itself will go unbalance.
In many ways, the shadow of a fallen is actually a far greater cheat compare to having the coin itself. The very reason why the shadow is not that much of a cheat is precisely because the shadow is bound to serve the purpose of the fallen creating it. Due to that restriction, shadow Lasciel cannot just grant Harry any knowledge Harry wants without a price. She has to bargain with Harry and in doing so increase the true fallen ability to influence Harry further. Lash however, has evolve to the point she can shrug off this particular restriction. She is free.
With the restriction gone, , Lash will be a cheat so frodulent Harry might as well become the MC of a Chinese Xuanhuan webnovel. Perfect memory, perfect recall, near perfect observation ability, virtual reality simulation capabilities, and the knowledge throve of a fallen angel. It is too much. This is Harry Dresden, not Leylin Farlier.
Sad though it was, Lash has to go.
I wish Jack Murphy has not died. The series is going more fantasy and less Urban these days. A truly strong and capable vanilla might strengthened the Urban elements.