(Myth units)
The Journeymen are an order that's split from the Heron Guard. The empire of Cath Bruig fell, and along with the remaining Heron Guards; the only survivors of the order were about 100 veteran members who were elsewhere at the time.
On their return to Muirthemne, they found their beloved Emperor's palace ruined. Each member took nine heavy gold tiles from the ruined walls, and hung them on their neck to symbolise their burden of guilt for being away when they were needed. The Journeymen also wear very heavy fur coats, and carry common laborer's shovels as their only armament. Almost all of them wandered to a self-imposed exile, away from everyone, feeling that was the right thing to do when they had no Emperor to serve.
On the battlefield, the value of the Journeymen is that they heal units, just like Heron Guards do. In the games, they carry six mandrake roots, enough to restore six units from near-fatal injuries to good health.
As with most Heron Guards, they have mastered the magical art of improving one's health and especially longevity. Most of the Journeymen lived long enough to see the conflict resolved, the empire of Cath Bruig restored, and to revive the order of Heron Guards to once again serve the Emperor.
Sources:
GURPS Myth
Myth II manual
http://myth.bungie.org/