Remove the pork tenderloin from the refrigerator, and allow to come to room temperature, about 1 hour.
Preheat an outdoor grill for medium-high heat and lightly oil the grate. Rub the pork with the olive oil, then sprinkle with salt, pepper, rosemary, and sage; rub the herbs into the pork.
Cook on the preheated grill until the tenderloin is crisp on all sides, about 15 minutes. Reduce heat to low and continue cooking, turning occasionally, until the pork is no longer pink in the center, about 60 minutes. An instant-read thermometer inserted into the center should read 145 degrees F (63 degrees C). While the pork is cooking, bring the blackberries and wine to a boil in a small saucepan over high heat. Reduce heat to low and continue simmering until the berries have burst and the sauce has reduced slightly, 10 to 20 minutes. Let the meat rest 10 minutes before slicing; serve with the blackberry sauce.
