If we are talking about V-Series Agents, we might as well talk about the secret Soviet Program to develop additional V-series compounds[1] that would be undetectable by the west. It is important to note that there are many vectors of entry for a V-series agent, and in this case, evidence points to an atomized version, as opposed to the dermal administration which is more common among this class. An atomized version targeting the respiratory system and not the dermal would explain why two women attempting to aid "with bare hands" would not have been harmed.

Beyond VX, there exist a plethora of other analogous chemicals, namely the G-Series[2], VE[3], VG[4], VM[5], VR[6] and VP[7]. A notable commonality among these compounds is that very little is known about their effects outside of military research (ie not shared).

Given the military nature of these compounds, there is a reason to believe that this was a military assassination.

[1] https://en.wikipedia.org/wiki/Novichok_agent

[2] Sarin is a G-series agent https://en.wikipedia.org/wiki/Sarin

[3] https://en.wikipedia.org/wiki/VE_(nerve_agent)

[4] https://en.wikipedia.org/wiki/VG_(nerve_agent)

[5] https://en.wikipedia.org/wiki/VM_(nerve_agent)

[6] https://en.wikipedia.org/wiki/VR_(nerve_agent)

[7] https://books.google.com/books?id=DQw2hVGe0aMC&lpg=PA72&ots=...