There is cold, and then there is COLD. Having spent our deformative years growing up in Fairbanks, Alaska, we know both kinds. Hell, school didn't close until it hit 55 below. When the temps drop far enough the risk isn't discomfort, it's losing fingers and possibly dying.
For that type of cold you need serious gear, and Rab is one of the elite companies that cater to you with clothing that will take you to the top of the earth and the bottom of the thermometer. Hands are probably the body part most at risk, and for that Rab offers their Expedition Mitten, ten ounces (per pair size medium) of hand warming 850-fill down-stuffed goodness.
A thick pile fleece inner mitten has small velcro tabs to keep it attached to the outer mitten, and a ripstop tab to pull it out easily for drying. No need for fine motor skills here, everything is fumble-friendly with large openings and easily adjustable cords. There is a lanyard keeper cord, a wrist cinch and a cuff drawcord that is quickly manipulated with teeth - don't wince, you know that's how you do it.
The ripstop Pertex Endurance shell is windproof and highly water resistant, and the palm is reinforced to handle ice axes and trekking poles. If you want to use gloves instead of the inner pile mitts, the weight drops to just six ounces for the pair, which is about as light as big mountain mitts get. The Rab Expedition Mitten is hard to beat, and you will never regret being able to pull these bad boys on when the mercury drops out. Highly recommended.