In Mistborn: The Final Empire, Kelsier's crew are holding their first major planning session. Breeze wonders why Kelsier can't send the fake Lord Renoux to the parties:
"Well, that should be easy," Breeze said. "We just bring up your impostor and send him into the parties."
Oh, he looks just like Lord Renoux. Exactly like Lord Renoux, actually. We just can't let him get near an Inquisitor.
If that's the case, why did the Inquisitor stick an axe into the kandra impersonating Lord Renoux during his battle with Kelsier? Shouldn't the Inquistor have observed that his target was a kandra? Afterwards, Dockson comments that the axe to the back might not have been fatal for the kandra.