+1 on the waved combo edge Endura or Delica- lightweight, positive lock, easy one-hand open and close, synthetic scales (vs. metal) for the cold.
I really like my Mini and full size Griptilians, but for the conditions you're talking about I would stay away from Axis locks and especially liner locks. Too much chance temperature, snow, or dirt could affect lock-up just when you need it most. The more it needs to work, the simpler I want it!
Also, since price isn't a problem, you might consider really thinking about what would be absolutely perfect for what you need in the way of features and have a custom made. I've seen some dedicated climbers knives, but they don't really seem suitable for you- very light and made to clip on to something- I'm guessing more for rock climbers in temperate conditions, but might be a good back-up for not much weight penalty. 2 is 1, 1 is none