This sentence uses the word "of" to create a metaphorical connection between the sun's reflection and the impending storm. The sentence doesn't explicitly state a storm is coming, but the "glint" is a sign, a "telling" that a storm is on its way.
Here are some other examples:
* "The silence of the room spoke of unspoken truths."
* "The dust on the old photograph told of a life lived and loved."
* "The tremble in her voice told of the fear she was trying to hide."
These examples show how "of" can be used to create a deeper meaning and create a sentence that reveals something more than what is explicitly stated.