Well, if it were David or Guy, for example, why would he need to hide his name? He is referred to as "The Nameless One"
The TRPG1&2 Hero had no name at all, his parents died when he was little, and he was powerful enough to destroy the Shadowling Queen.
I don't think there is anyone in the game likely to know all the skills taught, except Hero. I mean, will all his experience he could easily have seen backstab used, or even the bow attacks.
I dont see why David would hide his name, or why he would even have been in Ravinale.