Part of a dream, but also part of reality. Gleaning knowledge from a dream is the role of mystics and even some mages were capable of achieving such a feat. But this is uncontrollable, and hard to understand. Those born with it innately are desired everywhere.
And from the sergeant's words, this soldier of theirs was just that, someone who broke the spell in his own way and learned some of their enemies' secrets.
What specifically happened, the sergeant didn't seem to say so. The word of meeting that soldier never even came up. Which showed how much importance he was given at the moment, even showing that the soldier's future might not be as simple as he would have ever assumed.
Though, none of it mattered to Maisel at the moment, he understood why the sergeant brought him here and chose to expose him to such information.