Complex sentence: Before the march to the Black Gate, Aragorn confronts Sauron in the "palantír", however Sauron reveals to Aragorn an image of an unconscious Arwen, which frightens Aragorn into backing away, in which Aragorn drops the Evenstar and it shatters.
Split into simpler sentences: Before the march to the Black Gate, Aragorn confronts Sauron in the "palantír". However, Sauron reveals to Aragorn an image of an unconscious Arwen, which frightens Aragorn into backing away, in which Aragorn drops the Evenstar and it shatters.