1) Split open the vanilla pod and scrape out the pulp, and add the pod and the pulp to a small saucepan along with the brown sugar, lime juice, and salt. Whisk together and place the mixture over medium high heat and bring to a boil, stirring just until the sugar has dissolved. Remove from the heat and allow to sit for 2 hours before using. Remove the vanilla pod. Once cool, place the syrup in a squeeze bottle or other sealable container. Store in the refrigerator.
2) Preheat grill on high.
3) Peel and remove the core from the pineapple. Cut the pineapple into eighths, lengthwise, and remove any prickly brown eyes.
4) Thread the pieces of pineapple onto the skewers lengthwise. Coat the skewered pineapple on all sides with the syrup. Grill on all sides until golden brown, approximately 4 minutes per side, 12 minutes total, or until the pineapple is tender. Serve with any remaining sauce.