The Dīk Rūmī feather
One large stiff feather left where a watcher climbed in, and the only physical thing the party held on any of the six sellswords hired to hunt them
A single feather, large and stiff and clean, snagged in the collapsed roof of the derelict building beside the barracks the party had taken in Haudh-Gwenn. Somebody had watched them from that building in the night and had dropped in through the roof to do it. The feather is what he left.
It had not come off a wild animal, and Koa knew the bird: a Dīk Rūmī, a big ground-walker out of the cold, heavily forested southeast of Erôth. Its feathers are stiff enough to be the preferred stock for fletching arrows, which is narrower than it sounds, because a crossbow bolt is built differently and takes different feathers. So the watcher fletched arrows, and of the six sellswords Beltran Grayeras had hired to hunt the party, one was an archer.
They kept it. It was the only physical lead they had on any of the six.