There was a good reason for that, of course.
A shameful and ugly reason, but a good one nevertheless.
Soon after the second stage of the war started, the forces of both Domains had ventured to gain control over vast territories of Godgrave. The Sword Army had held a great advantage in that regard, already holding East Collarbone Plain and a large portion of the Breastbone Reach at the time, while the Song Army had been locked on West Collarbone Plain.
There were expeditions launched to conquer the two remaining Citadels in Godgrave. Revel was leading an expedition into the darkness of the Spine Ocean, and a Saint from the branch family of Valor was leading a competing one to make sure that the Lightslayer died there.