Unwrap the ham, keeping it in one piece, with its juices, and place it in a 2-Qt. slow cooker. Drizzle with the honey and place the lid on top.
Cook on low for 2 1/2 – 3 hours, or until ham is hot throughout. Turn off, but leave the ham in the slow cooker.
Drain the liquid from the slow cooker into a small saucepan. The total amount of liquid should be 1 1/2 - 2 tablespoons.
Preheat the oven to broil.
Prepare a small rimmed baking sheet with parchment paper.
Add sugar, onion, garlic, cinnamon, paprika, nutmeg, ginger, ground clove, and allspice to the saucepan with the ham liquid.
Whisk and turn to high. Bring to a rolling boil and boil for 1 minute, whisking the entire time. Remove from heat.
Place the ham, keeping it together as a whole, with the skin side up on the prepared baking sheet. Brush half of the glaze on the ham.
Place under the broiler for 30 seconds. Remove from the oven and brush on the remaining glaze.
Broil for another 30 seconds, or until the glaze is bubbling. Remove from oven. Serve hot, warm, or cold.