A glue stick used for attaching a blade to a composite shaft is a specialty adhesive that softens when heated. This allows you to remove a broken blade from a shaft and replace it.
But it is NOT the same as the glue used in a glue gun. Glue gun glue cools to a rubbery consistency. Stick glue cools to a hard plastic consistency and has a lot more strength.
You can heat and reheat the glue using a heat gun available at any hardware or paint supply. In a pinch, you can also use a hair dryer set on the hottest setting, but it takes a lot longer to melt the glue. DO NOT use a torch or open flame. You might damage your shaft and you will definitely void any warranty.