Dang, I am sorry to keep y'all hanging here for so long after starting the topic in the fist place;;
But I'm happy to see all of your replies! So now, after days of being a hermit crab and then forgetting I started this topic at all, I can try and actually answer you.
(Srsly, don't try to remember anything with a pregnant brain; it isn't your friend lmao)
It isn't too easy to discern one's own strengths and weaknesses, for sure. Mostly, the more experience we gain, the easier it gets, but I think it's safe to say that your strengths lie where your passion lies. I love characters and their interactions, so, naturally, I put most work in that skill over the years; but limited narrators tend to make it hard to describe the world, so that's my weakness—naturally, again. xD
It's not so much that I don't know how something looks; I can envision the scene just fine. But since I work with limited narrators (either 1st or 3rd person), describing the surroundings either results in something lackluster the reader can't really see (if I focus too much on the character's pov), or I risk getting in the way of the character, making the words sound stale and unfitting for the rest of the text.
I know the problem, I just can't fix it right now. Sigh. xD
What is your struggle exactly with action scenes? Can you pinpoint where they pose problems for you?
envy.png 
I think I could possibly lend a hand when it comes to emotions, though! Do you put yourself in your character's shoes, or are you more one to keep your distance when you write scenes that are supposed to be emotional?
That is super clever; I should try to focus more on that, as well. I remember one scene I once wrote (in German, sadly, so I can't share it right now) where my protag was just sitting in a cell, waiting to be interrogated. And he was bored. And I wrote the scene so that, when reading it later, I felt his boredom, but without being bored myself, but more amused with his thoughts (he contemplated throwing a chair around the room just to make things more interesting lol), and I was so proud of that one scene. XD
But I never managed to do it quite so vividly again, so definitely taking your approach to heart for the next edits of the chapters I'm gonna upload. <3
Have you tried developing the plot around the characters' wishes and goals? Maybe that could be an exercise when you struggle with character development. I always feel like plots that are driven by the characters (and not the other way around) are more engaging in a way? But that might just be a preference;;
How do you plan your plot, though? Do you have detailed outlines? Timelines? I don't work with any of that and pants my way through the story based on what my characters want to do at any given moment, and so far, it hasn't bitten me in the ass. 
Hm, I have a protagonist (in a story that's not yet online here) who's an arrogant assassin slash rude know-it-all. While not sympathetic, people find him interesting: his shattered psyche as well as his tendency to do the right thing regardless of personal feelings give him a depth that allows readers to root for him within the narrative, even though you would keep your distance from him in reality.
Maybe that spark of "interesting" is something you could work more on when it comes to your characters?