The poem treats the wind as something sick with a compulsion: it can't stop drifting out toward the sea. Calling this a "disease" is odd and a little sad, as if the wind's natural movement were a habit it can't help, not a freedom.
The wind is then measured against bigger things. It is quick, like a fleet of ships, but too small for "the great ice" and perhaps too slight even for a single ship on a still night, when there is nothing for it to push. So it seems restless and not quite powerful enough for the places it's drawn to.
The last two lines turn strange and quiet. The wind is "dancing" while "preparing for an ordinary death." The speaker seems to see something both playful and doomed in this, and the word "ordinary" takes away any drama. The mood is wistful and calm, with a faint, accepting sadness. Judging by the imagery, the wind may stand for any small, restless thing that keeps moving toward its ending.