Pg. 141
"Yet stray even a razor’s edge from the official Wallace narrative, and that razor will lash back straight for your throat."
Lash could in theory work here (very loosely, attacking/beating/retaliating), but with your use of the razor metaphor, I would propose slash as a more appropriate option. Lash is most often associated with something whip-like, not something razor-like.
"Yet stray even a razor’s edge from the official Wallace narrative, and that razor will slash back straight for your throat."
Possibly even:
"Yet stray even a razor’s edge from the official Wallace narrative, and that razor will slash straight back at your throat."