Waterdeep: How common knowledge is the dragonward?

[Chronos]

The city of Waterdeep is protected by an extremely powerful magical effect, called the Dragonward of Ahghairon. With limited exceptions, no creature of the dragon type is capable of entering a large spherical region encompassing most of the city. But how widely is this known? Does every commoner on the streets know "Yeah, you won't ever see any dragons around here, because of that big fancy spell Ahghairon cast a few centuries ago"? Is it an old legend that folks have heard of, but nobody's sure whether it's true? Forgotten to all but students of history? A state secret held only by the most knowledgeable of sages? And what about folks from outside the city-- Would they have heard of it? Only if they have good reason? Heard of it, but dismissed it as patriotic gloatings, of the "our city is the best in the world" sort?

I ask, because one of my characters is going to be a dragonborn. From what I've read elsewhere, the consensus is that dragonborn aren't stopped by the ward, but that it still has an effect on them, in the form of unsettling dreams and the like. Well, I can do that, and I think it'll probably add some spice to the game for that character to be getting these dreams that she can't explain... but the party is probably going to try to find an explanation. How hard is that going to be?

[Lunali]

I would say it's probably neither secret nor common knowledge. Something that anyone could find out if they were interested but not something that everyone knows. The origin of the ward is probably a little more obscure, but still available. The existence of the staff is almost certainly a secret and the current possessor of the staff even more so.