That wasn’t Shruiken, that was, like, a shadow dragon he summoned with his shadow power or something. Created for the movie so they could have a more exciting climax than a one on one sword duel ended by an elf magically shattering a ruby as large as a house directly over said duel before diving into it on the back of a pissed off dragon, providing the distraction needed for the hopelessly outmatched hero to stab the unholy abomination through the heart. That might sound awesome to you, because it is. Shruikan was the post credits reveal.