The item specifics in Auctiva is a pop-up window that comes up when you click on the item specifics link. That link is right underneath the spot where you select the category. The link is in blue text and doesn't really catch your attention because it is the same size font as the wording for the category stuff. Using it when you create a listing in Auctiva eliminates the need to go back to ebay to revise your listings just to add the item specifics.
Hope this helps!