Literary analysis: This verse is the "glory" half of the burning:glory reversal begun in the previous verse. In is the fire of the Lord (the true glory) that consumes the glory of Assyria's worldly wealth. What is burned is the "forest and fruitful field." While this is an image of the destruction of land, the addition of "body and soul" indicates that the land is also metaphorically the people on it.
The feinting of the standard-bearer refers not to feinting, but dying. the symbol of the nation lay in the standard bearer, and the defeat of a nation was symbolized by the standard coming down. Much of this feeling and imagery has been sustained in modern military lore, where tremendous valor has been exerted in maintaining the presence of the standard (or flag). It was even more so in the ancient world. The image here is of a standard falling, and therefore the nation falling before a more powerful force.