I agree with the previous speakers, summarize and add the following:
Non-lethal attacks fail if one uses...
...surfaces
...melee dmg with DoTs like bleeding, fire etc. pp.
...ranged attacks including spells
...shoving from elevations
As for pure additional damage from elements that is not considered a DoT, I cannot say. Likewise
Hunter's Mark with melee attacks? But then it would be buggy or the system doesn't distinguish well enough what is only additional damage but not a DoT. In conclusion, as RagnarokCzD recommended, any additional weapon buff should be avoided to be on the safe side.
