Well, this might be quite late. From my playthrough, I notice a few things. Besides from Ves and Roche feeling on the witcher's decision, there is also another consequence from the action which no one had mentioned before (from my search on the same topic). Not sure if I am wrong in my observation. If the witcher spare the Nilfgardian officer, the village of Mulbrydale do not suffer from any destruction. However, if the witcher decided to end the officer's life, the village will be razed. A few houses will be burned down and the armorer will be lost forever. You wont find the armorer in the village.
Hm, but in the current game version, the armorer does not move to Mulbrydale from his Person in Distress spot, anyway?
I have a different question about Eye for an Eye consequences. Ves in TW3 irks me so badly that I wouldn't mind failing Eye for an Eye - it's her choice to do a suicide attack, so let her have what she wants.
So, I know that this means that Roche won't join the Battle of Kaer Morhen. That is fine.
However, does it also mean that Reason of State won't happen and the north automatically gets Radovid?