How come the msq keeps using big words?

[Tohe-Spidhire]

I still think Urianger is just putting on an act or trolling or something. That takes some genuine effort to maintain that speech pattern despite literally nobody else anywhere ever speaking in a similar manner. Worse, he explicitly knows the people around him often have some minor difficulty in deciphering what he's saying, and yet still insists on being as archaically verbose as possible.

Dude's been in Eorzea long enough to pick up on the fact that he should probably consider learning how to converse with the locals a bit more efficiently.

Well, actually no.

Urianger is a researcher, seeking critical information about Primals. The other Scions are keenly interested in discerning facts from lore, and Urianger knows the importance of precise expression, leaving no room for ambiguity.

It would be foolish for any of them to discuss matters in layman’s terms (since misunderstanding leads to death), though I suppose Thancred’s manner reveals a touch of his criminal background.

[MistakeNot]

Well, actually no.

Urianger is a researcher, seeking critical information about Primals. The other Scions are keenly interested in discerning facts from lore, and Urianger knows the importance of precise expression, leaving no room for ambiguity.

A lot of his more obscure pronouncements is quoting old prophecies and the like - most of which are extremely ambiguous.

Urianger's problem is that he spends far too much time with really old books, and not much time with other people.
Think of him as someone who spends most of his time studying 16th century literature (Shakespeare and contemporaries) in the original language, and only occasionally mingles with ordinary mortals. It would be practically impossible for someone like that to not have their language coloured by their reading material.