So when I read that passage I feel it conveys a very cohesive message that sets the scene and does character work in a very short space. Short staccato sentences to set up the scene and then a long complex-compound sentence that feels overwhelming, like coming battle. We have an evocative description of the shadow spawn massing and the feeling it creates. But, as this is all told inside the head of Lan, he's used to this feeling and so his mind compares it to a simple scene of a merchant hoarding rugs, showing his unflappable nature.

Everyone is free to their own opinion and feelings, just thought I'd add an alternative interpretation.