[quote=@Hantu Kongkek]
Plus a class isn't as secret as the name; the class would be obvious the moment they do battle.
[/quote]

yeah, but at the same time it should not matter if you know their identity or not. However, at the same time you shouldn't be able to discern these traits at simple observation. You could just ask if you really wanted to though. It just seems a bit meta game-y to me tbh.

[quote=@Lonewolf685]
<Snipped quote by Hantu Kongkek>

Because Sasaki couldn't pass of as Saber. EMIYA was clearly an Archer when he pulled out twin swords. Medusa is obviously not an Assassin.
[/quote]

This is my take on it mostly.