I recently discovered an awesome tool called Affinity Designer. It's a vector graphics editor was originally for macOS. Before this, i was using Clip Studio Paint to draw the in-game items I posted before.
Since Affinity Designer is vector based, everything is a lot more precise than the rasterized approach I did with Clip Studio Paint. While yeah, CSP had vector layers too, I just never latched on to using it. With this however, it's a vector tool through and through, and then some. It's even got a side-by-side split screen view to compare your vector art to its raster counterpart so you can fine tune down to the pixel. Speaking of which, it also has a "pixel view" mode where you can make raster-based changes and it integrates seamlessly with the vector side of things.
I've read online that people are calling it an alternative to Adobe Illustrator. I can't confirm whether that's true or not because I never got into Adobe Illustrator or Adobe products in general. I personally just didn't feel like forking money over to Adobe every year.
Affinity Designer, just like Clip Studio Paint is a retail price purchase instead of a subscription model. That's one of the things that attracted me to it.
As for me, as of right now, I'm in the middle of recreating my items in Affinity Designer, while learning about the world of vector at the same time.
You can get Affinity Designer for $49.99 on their online store. They currently have an ongoing promo where if you buy it, you get a free copy of Grade UI Kit which is a collection of UI materials for use in the program.
