just as "v" in Latin makes a "u" sound. v=u.
You have that wrong. The common way of pronouncing "v" is as you would a "w."
Veni Vidi Vici = Weni Widi Wiki
I get that.. But, why wouldn't everyone call it "Kai-Zars" leigion?
Why would NPC's in F:NV say "they call themselves "See-Zars" Leigion?
you know?
Caesar himself has extensive knowledge of the ancient Roman Empire. Hence why he based his own empire off of them. The reason the Legion uses the proper pronunciation is because Caesar taught them too. The reason the other people use the English pronunciation is because they probably don't even know who the Romans were. This was confirmed by Sawyer, I think, before the game was released. It's just a flavor thing.