Weird english

[Berethos]

"pray seek" "is aught amiss" "Come for succor"

I think you're misunderstanding why they have some characters talk like that.

For Minfilia? It's meant to give her an air of both politeness and sophistication. Generally the more "sophisticated" or "refined" a character is meant to be, the more frequently they use words like succor and phrases like "is aught amiss" or "pray seek" (Alphinaud is another that often says things in that manner, and it's meant to be set him apart as one of scholarly upbringing). Rougher or less refined characters tend to not use those phrases...which reaches its ultimate form in those like Jacke or other Lominsans who use a pirate-like dialect, meant to indicate their typical lack of sophistication and schooling.

It's not meant to just say "Hey, our localization is different and flowery" it's meant to help show differences in different types of characters through the use of language (namely dialect, slang, and vocabulary). It's a subtle hint (or in some cases, not so subtle) at differences in social status in the world of Eorzea. There are plenty of examples of similar differences in English alone in any number of the countries that use it as a primary language, and I'd be willing to be there's similar differences in the types of words used (or how they are said) in many other languages, including Japanese.