"Of all the other archmages destined to become legends who took part in the Great War, none would compare to the following individual".
For anyone who doesn't realise, this is the text in GURPS Myth before the paragraph concerning Mazzarin.
This seems to say that Mazzarin took part in the Great War, yet strangely enough in the next paragraph it aknowledges that he died many decades before Connacht defeated the Trow, and we know that he died during the Wind Age. So how come Mazzarin was involved in the Great War? Gene Seabolt skipped the levels and so could not have seen the Mazzarin in the Watcher level (something which will need to be confirmed), so he must be referring to someone else.
Maybe this Faceless Man is Mazzarin...