i have always loved the style of those floor length coats from the 90s, so my first real purchase was a COS dark navy 100% wool coat, lined, belted etc. that stops a little over mid-calf(?), bought sometime around 2013-2014 on flash sale, back when I was working full-time.
Don't have it with me rn because I'm in very tropical climes, but link for reference, maybe that's the right coat? Anyway it used to be really itchy but a few years now, it is the softest, warmest and lightest winter thing I own. It has also received mass compliments, so yeahhhh frankly the best investment ever.