From official GW:
It's time for another Guild Wars contest! And with the Design-a-Weapon Contest, you have a chance to be immortalized forever in the second chapter of the Guild Wars story. We will be offering many new weapons and shields in the upcoming installment, and we'd love to include items based on your concepts. To enter the contest, simply send us a drawing, sketch, or printed image of a weapon or shield that you have designed.
Specifics, Rules and Regulations can be found HERE