Place butter, honey, brown sugar, and lime juice in small saucepan. Scrape in seeds from vanilla bean; add bean. Bring to simmer over medium heat, whisking until smooth. DO AHEADCan be made 2 days ahead. Cover and refrigerate. Remove vanilla bean and rewarm sauce before using.
Prepare barbecue (medium-high heat). Brush both sides of pineapple with some sauce. Grill 1 minute per side. Transfer to plate; cut into 1/2-inch cubes and place in large bowl, leaving juices behind. Mix remaining sauce into pineapple. Cut bananas into 1/2-inch chunks; fold into pineapple mixture.
Image Credit: Antonis Achilleos
Recipe courtesy of: Dede Wilson