Kinda feels like people are reading too much into this. The trailers have always had the warrior of light changing jobs in the trailer. This kinda looked like he was being stripped of his skills and being knocked back to his ARR status as a warrior to me. Possibly just symbolism for a story point.

Also arbert, the warrior of darkness was a warrior as well. Seems foreshadowing of our need to follow in the footsteps of the warrior of darkness.