The "solution" / the reference from Novalion
can be confirmed:
But i want to explain the (imo.) easiest way:- Chapter 3 "Wolvercote Catacombs"
- recommendable to do this with a coop partner but also possible playing alone
It's not allowed to kill enemys "directly".
So the sword / hammer / arrow are useless for this achievement.BUT
if you kill or push enemys with boxes / plankes from the magician this won't affect the achievement.
Also pushing them into thornes or pits is possible.
With an combination of "skipping enemys by running through" & "pushing them with boxes and planks" you can run easily through the level.
In this Chapter is also a boss (a big Skeleton with a sword). It's the only enemy with a health bar in the upper right corner of your screen.Killing him with the sword or bow won't affect the achievement.
If you think that there are other parts in the chapter which are complicated and should also be explained by me please let me know.
If there are some mistakes or misunderstandings in my translation, please let me know. I'll correct that immediately.