Yes as model for left arm has rather noticeable gladiator shoulder plate on it as it is used by Retiarius gladiator. Right arm model is just missing that plate but I can't simply mirror that model to other arm.
As you can see on below picture, it has to distinct look to be used for other units:
https://lh5.googleusercontent.com/-M...s_plate_01.jpg
But with shield on left arm, lack of protection will not look bad and might even make sense (since various manica and other arm guards were not used for shield arm if shield was present).