I think the gloves vs. mittens (or any combination of either) depends on what you're doing (how much finger dexterity you need).
But yeah, the weather forecast promises -20 Fahrenheit /-30 (or so) in Celcius for next week here in southern Finland and presently if you step outside, you'll end up knee-deep in snow (except for the bits the plows have visited). I kinda got the idea from GRR Martin's Song of Fire and Ice that at least the Wall had similar weather conditions and, well, if someone can get used to standing guard outside at -20F without a hat and a ton of clothes on them, they get my respect (and sympathies) for being much tougher than I
About 10 years ago I stood at a line party in around -18F / -28C for a tad over six hours with only one pair of gloves and socks, long undies, jeans, t-shirt, sweater, and a jacket. Once I got inside, it took around half an hour before I could even feel my fingers/toes again. Oh, and I had holes in my gloves and shoes. Yes, I was an idiot (some argue I still am).
Probably the biggest pet peeve for me in fantasy is combat (be it about melee weapons or guns or whatever). It's such a rare treat to read anything that's even borderline realistic and at least for me a book can end up wallbanged if the fight scenes are, well, silly (unrealistic). At least if the overall tone of the book is realistic because if it's obvious the author has thrown any notions of realism out the window, it wouldn't make much sense for them to make an exception when it comes to depictions of combat. The reverse, however, is far more common, alas.