I got this blazer in a couple of weeks ago but have been too busy to properly style it and make a decision until now. If you'll remember, I was initially undecided about whether to get the size 8 or size 10. I've decided the 10 is too big in the arms, shoulders, and bust so I'm either keeping the 8 or nothing at all. I don't want an oversized-looking blazer, I want a tailored-looking one. The 8 looks slightly tight when buttoned but like many people mentioned, nobody ever buttons their blazers, least of all me, so it's not an issue. The 10 is the one in the last photo just for reference, everything else is the 8.

I've styled it with a few different types of tops (note: these are not necessarily entire outfits that I'd actually wear, I was more interested in seeing how it would work with different TYPES of tops.) I took back photos of all of them because the fit in the upper arm and back is what I'm most interested in. It feels ever so slightly tight in the upper arm with the long sleeved layers, but not constrictingly so. You can see that there's some slight weird pulling at the upper back from the armpit diagonally upward. I believe this is exaggerated in the photos because ironically I am standing up straighter than I do IRL (hence pushing my shoulders back) and because I had to significantly bump the exposure on the photos to see any detail. Also, the vent at the bottom is not cut open yet, and I don't know whether that would release some of the pulling as well. I guess my biggest question is whether or not you think that creasing at the upper back is a dealbreaker.

Photos:
1-4: with a black medium weight shell. This is probably how I'd be most likely to wear it as I generally prefer to wear blazers over sleeveless or short sleeved tops.

5-8: with a thin, long-sleeved buttondown shirt. I didn't realize the front was crooked until I saw the pictures, so please excuse that.This felt fine except for the bunchy feeling I always get with long, loose sleeves under jackets (not a tight bunchy feeling, just an excess fabric feeling).

9-12: with a lightweight long sleeved sweater. This is probably the heaviest thing I would ever wear under it. It felt slightly tight in the upper arm but didn't hamper mobility. #10 is with it buttoned just for kicks, but I do think it looks too tight that way. (Someone on my previous thread suggested moving the button slightly, which I may try if I decide to keep it.)

13: size 10 for reference.

By the way, the skirt in the first set is also new, I added the find below.
Uniqlo calls it a "sweat skirt" but it actually surprisingly turned out
to be more like a pencilly tube skirt. (I was actually looking for a
more casual one as a replacement for an old skirt, but it was cheap and
will be useful.)