To be fair, these heretics were actually quite cautious.
They didn't believe Duncan simply because he produced the Sun Amulet, nor did they readily trust his account of what had happened at the sewer sacrificial site. All along the way, they observed Duncan's words and deeds, and even after arriving at the meeting place, they conducted an additional verification to confirm the identity of the stranger—considering they were heretics who had to skulk around, they were doing their best.
But all their screening measures were designed to deal with Duncan as a "normal human being."
To the captain of Homeloss, these means were meaningless.
The tall and thin ringleader took back the inconspicuous strip of cloth from Duncan's hand, apparently unaware of any change in the power within this transcendent item. After expressing his welcome to the new comrade, he gestured towards a corner of the meeting place, "Comrade, rest here for the time being. You're not the only unfamiliar face here."