I have no dog in this fight so I asked my Dad (GrudgeBringer) who used to almost exclusively play EA Arco about the Skeptics.
His answer did surprise me.
He said that he also used Skeptics as scouts but had to be very aware that the "Usual' rule of thumb was....ANY Mage, Priest, or troop of any kind that can do harm to another nation in any way in the other nations territory could be considered an act of war.
So, I asked a specific Question about skeptics. His reply was that skeptics hurt domain and cause unrest. He would try and get by with one or two as scouts but if caught he would have to make some diplomatic amends and at times was summarily attacked with out warning.
So while it doesn't sound like you meant any harm or knew any one would take it that way. It did sound as you meant to run skeptics knowing they would lower Domain.
I am not suggesting he attack you, but now I guess If I found skeptics (OR a stone idol etc) in my domain, I would probably demand compensation or attack (LOL, or cry).
I didn't know Arco had so many small weapons at its command.
