"Well, I am not really worried about his strength or the powers he may have; what I am concerned about is that Nathan knows too much…"
"He may spill every secret to the 'False Dome' cult…."
As a grade 1 mage, Nathan obviously had a massive detection range, and he also had a massive information gathering network.
He knows many secrets about the empire's army and weapons. He knows about the 'Seals of the False Dome' and he knows about many other forbidden things.
This knowledge may not be of much use to the humankind, it is certainly worth the attention of the 'False Dome' cult.
Thomas clenched his fist and asked Jareth in a solemn voice.
"If he gets corrupted, what shall we do then?"
Jareth's answer to the question was very simple.
"What else… We will destroy him right then and there…"
Jareth's words carried the same coldness as usual; he was ready to deal with a time bomb like Nathan whenever the opportunity arose.