The shaking of the lulav might be like shaking by davening based on the pasuk כל עצמותי תאמרנה ה’ מי כמוך, all my bones recognize your existence Hashem. Rav Moshe ztz’l stopped shaking by davening based on a story I heard. A nazi german soldier pointed a gun on him. He said this shock I have I want to remember and use it at my davenen.
