In a medium saucepan, melt the butter. Add the chopped sweet onion and cook over moderate heat, stirring occasionally, until the onion is softened and lightly browned, about 5 minutes. Add three-fourths of the minced habanero chile and cook for 1 minute, just until softened. Scrape the onion and habanero into a blender, add the cherry preserves and lime juice and puree until smooth. Return the cherry glaze to the saucepan and bring it to a boil over moderately high heat. Stir in the remaining minced habanero chile and season the glaze with salt and black pepper. Transfer the glaze to a small bowl.