See some of them fully did not either. Yammi was a Vastro Lorde and yet he has more mask than most of them... so the mask does not AS much in this (in reference to how much they have showing etc). That is my take on it at least... He was as well as Ulquiora. If I was not mistaken (which I could be
) Vastro Lorde was the ALL of the Aizens experiments and the Espada was the term for the top 10 Vastro Lorde. Like calling comeone captain does not mean they are not human, it is a rank. So therefore they are STILL Vastro Lordes but they hold the title of Espada. *Just my (whatever its worth) 2 cents, haha.
