Why is it phrased like that?

Old fashioned. Very clearly linked to how modern German would ask it. "Was sagst du, Mary?"

We phrase it like that sometimes here in Alabama in a sarcastic way. Example, we already know the answer but just want to know if you will be honest.

It's an archaic word order for questions in English. It's still perfectly valid in modern German, Norwegian, and many other languages. But modern English has largely abandoned it.

**What say you** and **how say you** were procedural questions in law courts a few centuries ago. We encounter this usage in older novels and in modern historical dramas in film and television. Occasionally today a person might ask someone what they think about something using this old fashioned expression but only in a lighthearted fun way, fully aware of the fact that it's now archaic.

What did u say? , say what!! , what do you say ?

It's a fixed expression, a leftover from back when German and English were much closer.

It's just archaic

In English, all the way up until early Modern English (1600s or so), in a question, you would simply switch the order of the subject and verb. So '*He goes to the store*' could be written as a question as '*Goes he to the store?*' Actually, it's *still* the case, but now we virtually always use an auxiliary verb, and it's the auxiliary verb and the subject that switch order. * He eats. * He is eating. * Is he eating? * What is he eating? Or another example: * She reads a lot. * She does read a lot. * Does she read a lot? * What does she read? Note that, in addition to some stock phrases like 'What say you'? the verb *to be* never needs an auxiliary: * He is the boss. * Is he the boss?

You might see and hear it today, but almost certainly in a whimsical manner.

I would agree with u/kw3lyk for the most part. The entire paragraph is written in antiquated but not archaic English. To say that a phrase like "What say you" is hardly ever used is more or less correct in the sense that it is certainly not part and parcel of everyday speech, but I can think of occasions when using that phrase would not be considered inappropriate or awkward. If a conversation goes along the lines of, "Well, I've told you what I think. Now, what say you?" or something similar, there is generally some emotional content conveyed by the unusual choice of phrase. It could be, for example, exasperation. This sort of thing is very context-dependent and my best advice for non-native speakers would be to avoid unusual constructions because, probably more often than not, a non-native speaker is going to convey an unintended meaning.

It’s just archaic. Nothing more to it than that.

The whole paragraph is written in a style more common about 200 years ago. You are either reading something old, or the author is intentionally writing in a style to mimic that time period.

Flipping the word order of the subject and verb in a question is a proper and literary technique in English.

Lots of people saying this is archaic English in this thread (and maybe it is for some dialects), but "What say you?" is still used as an occasional stock phrase in British English. When its used it is usually done so to indicate that the opinion of the person being asked is of some importance.

It's just an old fashioned, literary way of phrasing it. You will hardly ever hear people say it that way in real life conversations.