All those images represent are the race/class combinations. Dual wielding warriors in DAO aren't discounted by those images or dagger wielding rogues would be as well or twohanded weapon wielding warriors.
And if, not likely, the images only depicted the weapons you can use for each class in DAO but it doesn't show dual weapons for a warrior warden I don't see how that would proof the warden will appear. If the images did show the possible weapons per class but not dual weapons for a warrior warden there would be slightly more proof against the warden appearing, not for.
They represent the class, yes. However, it's just interesting to note the lack of said items. Maybe it means nothing, sure. But at the same time, I doubt we can choose our abilities in the Keep, and therefore, were the Warden to appear, it's easier to represent his/her class skills via the new system were they to ignore certain factors such as duel wielding.