This is not a metaphor or a general description.

It is a specific observation by Denig, who understood what the devices meant because he had spent twelve years watching Crow warriors assemble their robes through accumulated deeds.

The fact that her robe carried these devices means that she had done the specific things that produced them — that she had counted coups, taken horses, led raids, and performed the specific deeds that Crow warrior culture recognized and commemorated.

Her status as a chief was not a title conferred by sentiment or tradition.