It looks nice, but I think your animation is really unrealistic. You can’t just hold such a crossbow in one hand and tension it with the other hand. Theres a reason why that model has the metallic thing on the front:
http://www.benjaminrose.com/wordpress/wp-content/uploads/2012/11/crossbow-goats-foot.jpg
There might have been some crossbows that you could tension while holding them in one hand, but the one you modeled is definitely not one of those. For that model you have to use a foot.