Just for fun
Ice skates could be used to go at full speed on the frozen lakes without draining energy, should use metal, wood and leather
Sledge could be used to quickly go down the hill if it has snow. Skis if equipped should increase player's speed on snow area. Both should be able to be packed into inventory, then equipped. Maybe it would be nice to use them to quickly escape from mammoths/other aggressive players in mountains.
Maybe, a large sledge could be used with horses with several people sitting in it, then no slope would be necessary.
Also, all above would be nice to have if seasons are implemented.