Blunt, brusque, curt, and terse -- is there a gradation of connotation here?

I have two related questions.

1. Do each of these 4 words have negative connotation regarding intent? (E.g., rudeness, malice, inappropriateness, etc.)

2. If so, is there a gradation (or scale) of rudeness or negative emotional connotation associated with each?

   • If I wanted to describe myself as someone who responds to questions in a manner that is to the point, short-worded, professional, etc (and not reacting to emotion or demonstrating sympathy), which word would adequately describe myself without carrying negative connotation (since I wouldn't want to associate a negative adjective to myself).

Please provide support for your answer!!

Although this SE question addresses brusque vs. curt and this SE post addresses blunt and brusque, the answers to both questions are mostly contradictory, incomplete, and unsupported.

I can't support my answer with references, but FWIW, here's one native speaker's data point on what the words mean to me.

• A blunt remark is abruptly harsh — compare "hit with a blunt instrument." It specifically implies that the speaker is not taking the time to soften the metaphorical impact of their words (for unspecified reasons). I suppose it's possible for someone to be blunt without being concise. All four words are concerned with the speaker's delivery, but blunt is the only one of these words that implies something about the surface meaning of the speaker's remark.

• A brusque remark is businesslike. It may indicate that the speaker doesn't suffer fools gladly; which might imply that the speaker thinks the listener is one of those fools and doesn't merit a longer reply.

• A curt remark is abrupt and delivered impolitely. (A blunt remark is abrupt and delivered naïvely without consideration of etiquette; a curt remark is abrupt and delivered in deliberate contravention of etiquette.)

• A terse remark is brief or concise (for unspecified reasons). It is certainly the least "loaded" of the four words you mentioned.

The positive-connotation word you're looking for is indeed probably concise. Another word not yet mentioned is economical (but it has an ironic connotation to me: if you're economical with your words, whose resources are you really interested in saving?)

Other alternatives suitable for résumés: direct, to the point, or the stock phrase clear and concise.

Blunt can mean with intent and brusque also implies rudeness. Those words can also describe someone's character, which they often don't have much control over.

The only one which I would ever use to describe myself publicly would be blunt², as in this example

I am going to be blunt with you, because time is short and this is a serious matter.

None has a positive connotation, or would be good to apply to yourself, but you could describe your answers in a positive way with, from Lexico

concise
ADJECTIVE

Giving a lot of information clearly and in a few words; brief but comprehensive.
Compared to the seeming waffle of Chamberlain, Churchill's account was clear and concise.

So you could say

I respond to questions in a concise and professional manner.

I'm sure there's never been done an experimental study of the emotional impact, measured through skin conductance or through a simple questionnaire (similar to what produced this), of each of these words. Maybe one could extract a word2vec embedding and then compare cosine distances and directions on relevant dimensions. I think you'll have to rely on a qualitative comparison possibly but not necessarily backed up by dictionaries, which may or may not provide enough nuance to distinguish what native speakers do very successfully. Also, there's a lot of overlap.

For the logical concept of 'expressed in few words', there are a number of synonyms (I'm sure there are many more):

blunt curt brusque terse abrupt clipped blunt gruff short brief concise succinct compact crisp pithy incisive economical laconic epigrammatic telegraphic

They all to some extent provide a nuance that is different in some direction that could easily be explained with more words and would help distinguish.

But at a first pass, one could place them on a continuum of rudeness; there would surely be some overlap between neighboring ones but more sure of the difference towards the ends.

For example, 'terse' is not rude at all, but 'brusque' is. 'Blunt' is surely a shorter message, but also has the primary meaning that it is too honest. 'Curt', from the French for 'short', is slightly rude but doesn't have the connotation of too much honesty, just short.

All the following are the canonical entries (for comparison) from the OED:

blunt - 5. Abrupt of speech or manner; plain-spoken; curt; without delicacy; unceremonious.

brusque - 2. Somewhat rough or rude in manner; blunt, ‘offhand’.

curt - 2. a. Of words, sentences, style, etc.: Concise, brief, condensed, terse; short to a fault.

terse - 3. spec. Freed from verbal redundancy; neatly concise; compact and pithy in style or language.

As you may well be aware, there are no exact synonyms. If a word is differently spelled, it has -some- difference. It may be negligeable, and it may lead to semantic drift or even swapping of meaning (viz. uninterested and disinterested). Just because some of the above definitions use another word in the list doesn't mean they are replaceable in the exact same circumstances and lead to the same communication. From just the dictionary entries of blunt and curt, I'm failing to distinguish them, even though I know it is not written there that blunt is much more evocative of something physical (it could be used of an object), where as you can't apply 'curt' to objects, only utterances.

So if forced to answer on the rudeness-politeness scale, terse is neutral, and curt, brusque, and blunt are roughly all 1/2 way to rude with a wide spread depending on context. Much of the latters' rudeness is from context and not so much inherently in the word itself. They are not equally all the same distribution.