Cold, wet, windy. -20 to + 5 celcius. Open tundra to pine forest. Think Tutenborge Forest in Germany.
You mean the Teutoburg forest (historical battlefield where Arminius destroyed the Roman legions)? I'm not sure that's a good comparison to Scandinavia. Also, tundra has very little in common with boreal forest.
Anyway, I live in the temperate zone but the temperature range you've just described is typical for our winter. I've never seen anything that would indicate 440C is any more brittle at low temperatures than any other stainless steel.
I'm sure the Fallkniven F1 would be a good choice for the Northern European environment or any other place with a cold climate and lots of forest. So would a Mora (at a fraction of the price), the fixed-blade Benchmade or even a Kabar if you need something closer to a tough sharpened prybar that still makes a good knife.
IME, if there is one truly indispensable survival tool in the North European (or equivalent) environment it's a good axe. Probably even more important than the knife. No matter what kind of knife you have you need an axe to make a decent shelter, fell trees and split logs in the cold, snowy coniferous forest zone. Without that capability your chances of survival drop rapidly.