First, make the honey-sage simple syrup: Place the honey, sage and two tablespoons of water in a small saucepan and bring to the boil over medium-high heat. (Alternately, you can heat the honey, sage and water in the microwave for about 30 seconds or until it bubbles.) Set aside to steep for 5 minutes then strain to remove the sage. Set aside to cool.
When you are ready to assemble the margaritas, dip a q-tip in the honey-sage simple syrup and run it around the rim of your glasses (or use your finger). Place the salt on a small plate then roll the honeyed rim of your glasses in the salt. Fill the glasses with ice.
In a large shaker, combine 1/4 cup of the simple syrup, the grapefruit juice and the tequila. Fill about halfway with ice. Shake for 30 seconds then strain the margaritas into glasses. Garnish each with a sage leaf and serve immediately.