Upon further evaluation, it seems like you can 1-hit or not 1-hit crows both in vanilla and NTT - this depends largely on whether you are swinging the wrench in open space and on the distance to the target. In open space, the crow is pushed alongside on a swing (like a board on a wave), dealing more damage. If the swing touches a wall, on other hand, it advances slower than the crow is pushed away from it, and thus does less damage. Only narrowly reaching the target with a swing results in a similar effect.
Hmmm really? I never noticed crows on steam live (98) needing two shots with the wrench and scarier face.
EDIT: Totally forgot to say which version I was playing prior to NTT. But yeah, 98 never gave me that problem.
EDIT2: Just tried to replicate the 2_hits_needed on live and couldn't do it. Every crow would die in one hit from scarier face...
Upon further examination, the issue was identified to be because the act of ravens having their health and max health reset during flight, with "flying" object also being exempt from Scarier Face' rules (meaning that they'd go from 8/8hp to 10/10hp).
Narrowly hitting with a wrench (only dealing damage once) does 4hp damage, full hit does 8hp damage, so that explains it.