Still haven't looked at the files yet, but before I do I can almost guarantee you that those are Alex's eyes and Alex's teeth. What you have to do, using Blender at least, is import Alexander, select the entire breastplate (or whatever you need to use) then separate it. After you do that select whatevever it is you seperated and invert the selection so that everything else (including the bones and eyes and everything) is highlited and then delete that. Then EXPORT whatever is left (i.e. what you want to use) into a folder, call it whatever you want (I would call it ArmorCaesar or something). After you do that start up an entirely new file. After you start a new file IMPORT CAESAR, once Caesar is imported then import the armor. place the armor on Caesar properly (you might have to reshape it, I find it easiest to use the scale on axis feature but you can do whatever you want), after this is done rig it to the torso by selecting the entire thing (best to do this in edit mode), and then going into object mode, after that HOLD SHIFT and click on to caesar's body (anywhere will do) and JOIN THE OBJECTS, then go back into edit mode and in the bottom corner choose the torso "bone" and apply it to that. To see if this worked deselect EVERYTHING and then select everything rigged to the torso. If you did it correctly the armor will be highlited along with the rest of his torso. After this make sure you CTRL+A to apply the resizing (if you did any) and then export the nif into the same folder you imported the armor to (just to make it easier on you). You should also SAVE at this point just in case.
Then go into Nifskope and open the REGULAR JULIUS CAESAR nif. You should also open your exported nif (the one with the armor). This is important and I don't mean to be condescending by doing this, but you really need to read this part...
ALL YOU HAVE TO DO IS SWAP THE ARMOR OVER TO THE ORIGINAL CAESAR, THAT'S IT. IF ALL YOU ARE DOING IS ADDING ARMOR THERE IS NO REASON TO SCREW AROUND WITH ANYTHING ELSE. JUST SELECT THE ARMOR FROM YOUR NIF, RIGHT CLICK AND COPY BRANCH, THEN GO TO THE TOP IN THE LEFT WINDOW THAT LISTS THE NODES AND RIGHT CLICK THE FIRST ROW AND PASTE BRANCH. IF YOU DID THIS CORRECTLY THAT SHOULD BE ALL YOU NEED TO DO.
That's basically it. Oh yeah, and I'd advise that you save the nif once the armor is on as something else, like "armored_casesar.nif" so you don't lose the original.