In a saucepan, combine brown sugar, butter, honey, mustard, apple juice, and pinch of salt; whisk and cook over medium high heat until well incorporated. Continue to cook for 5 minutes.
Remove from heat and set aside for a couple minutes.
Pat dry ham with paper towels and transfer ham to slow cooker; set aside.
Pour 3/4 of the glaze over the ham. Using a pastry brush, just brush it all around and in between the slices.
Cover slow cooker with lid and cook on LOW for 4 to 5 HOURS.
If the ham is too large and can't close it with the lid, use aluminum foil to make a tent over the ham. Then, cover with a kitchen towel and cook.
Baste ham with juices every hour.
Preheat oven to 400˚F.
When time is up, remove insert of slow cooker, keeping the ham inside the insert; brush remaining glaze all around - if the glaze has thickened or hardened , heat it up before adding it to the ham.
Bake ham in the oven, uncovered, for 15 to 18 minutes, or until top has caramelized and browned.
Remove ham from oven and transfer to a serving plate.
Spoon juices over the ham.
WW Freestyle points: 12