a model that has a basic bone skeleton, but not a full rig, is 'skinned' this can support simple animations and is what dbpro handles mostly due to the .x format
a fully rigged model has controls to aid in animation, manage inverse kinematics, constraints, focus targets etc, this sort of thing is a bit beyond what .x can handle, but can be implemented in dbpro via code.
that being said, im still a little confused about your goal. are you ultimately going to be using sprites or objects, programming with 2d commands or 3d commands? if what you are after is an animated sprite sheet of isometic images, it really doesnt matter how the artist goes about making it. this could be produced by a 2d artist, or rendered out by a 3d artist.