This is also the last skyshard on this list found outdoors. The altar mentioned in the title is important, as you can’t reach the shard in the area of the crafting station. Your exact goal is almost in the middle between this crafting station to the west, and Hjaalmarch Great Lift to the east. The closest Wayshrine is the Morthal settlement one, to the east.
If you are coming from the closest shrine in the east, cross the river and head toward the Hjaalmarch Great Lift. Following the main road, start ascending the hills toward the south. Soon enough, you should spot a small, unmarked settlement with a large wooden tower – a watchtower. Anyone on this watchtower would have a great view towards the smaller hill in the west. This hill is where the altar we are looking for lies. Climb on the hill, and there, on a rock nearby, is a skyshard.