Birds of a feather flock together. Achtreal had not been the only territory that suffered under the rule of a tyrannical Noble in the area. Its neighbouring territories also suffered from the same problem. Therefore, when the news about Achtreal's liberation was spread, many of the Nobles who governed the territories sweat coldly.
This, of course, didn't change anything. If any, the people got treated more harshly than before. The Nobles believed that treating them fairly would only make the people get cocky. By treating them more harshly, the Nobles were certain that they would forget the idea of rebelling.
Many were executed because of a mere accusation. The fear of getting accused of being a potential rebel was rising every day, so it was natural for the Nobles to believe their method was effectively working.