I think it's fairly clear that Valkyria Chronicles III is aiming to strike a slightly edgier tone than its previous incarnations, what with its black-ops squad of "Nameless" soldiers conducting secret missions in the midst of the Imperial invasion, it's only fitting that the deluxe (hence "DX") edition of the game comes with some edgier bonus bits.
And nothing's edgier than...a cup. And not some kind of ugly-ass mug that says "World's Best Nameless Soldier" on it, but a wartime cup, which is collapsible, the better to fit in your nameless soldier rucksack. So when you get your DX edition, you can drink your black coffee out of a wartime cup, all the while smelling that burning Ragnite on the battlefield.
Oh, and it also comes with a clear poster, and "Gallia Secret Document", which spills some of the details male lead Kurt Irving's last mission as "Kurt Irving". Check out some spiffy picturesof the cup and its branded metal container below. Another, retailer-exclusive DX edition comes with dog tags for characters Riela and Imca (pictured above), but dog tags are so done-to-death. This is a cup. For drinking!
It's just better.