Place the ham in a small roasting pan, cut-side down, and pour 1/2 cup water into the bottom of the pan. Cover the pan tightly with foil. Bake until the ham is heated through, about 1 1/2 hours.
Meanwhile, combine the honey, brown sugar, butter, Dijon mustard, whole-grain mustard and thyme in a small saucepan. Cook over medium-low heat until the sugar has dissolved, about 2 minutes.
Increase the oven temperature to 375 degrees F. While the ham is still hot, remove the foil and carefully pour off the water from the roasting pan; it is fine if a little water remains. Brush about half of the glaze over the ham. Return to the oven, uncovered, for 5 minutes, until the ham is golden brown and beginning to glaze. Brush with the remaining glaze and bake for another 7 to 10 minutes, until the ham is well-browned and glazy; be careful not to let the glaze burn. Serve warm.