Still not how the byzantine army worked. Or any eastern nation with anything resembling a standing army.There will be "men-at-arms" in stead. They sound like retinues (high quality troops whose unit composition you can choose), but are raised like levies. So closer to how armies of the era functioned, with vassals supplying a certain number of troops equipped a certain way in times of war, but not having them be a standing army.
Perhaps the Knights will have honor guards that are always "raised", but so far we don't know.