Weirather posted her first career World Cup victory with a time of 1 minute, 19.82 seconds, 0.12 seconds ahead of Mancuso and Maze.
Anna Fenniger and Nicole Hosp took fourth and fifth places, respectively, on a day when weather and course conditions at Garmisch were described as ideal.
"I managed to keep up the speed all the way down," said Weirather, who has battled knee injuries for much her career. "My shin isn't hurting anymore and I could really push on it. I was really fast in the last section."
The tie for the second spot also tightened up the super-G standings. Maze, the overall points leader, also maintained her lead in the super-G category -- by a slim 65 points over second-place Mancuso with two more events left in the season.