Warm Hands
Just like your body, Layers, Layers, Layers! Thin poly glove liners, heavier poly gloves, heavy poly mitts, & 2 pairs of Goretex or similar mitt shells. Use them alone or various combinations. And take more as needed for wet conditions. Also key, as mentioned above, keep the rest of your body fueled, & warm, and your hands will be happier. Take more small stops rather than just a couple of long rests. If they do get cold, loosen your grip on whatever, and wiggle them a little. On the flip side, you can cool yourself down by removing your gloves &/or hat.
Enjoy
Tom