"This victory means a lot to me after all the problems I had this season," said the 28-year-old Hoefl-Riesch. "I had health problems and I went out a lot."
The German, who has won only one World Cup slalom this season, was the most consistent of the field to clock an aggregate time of two minutes 39.92 seconds from the morning downhill run and the afternoon's slalom.
It was the 2011 World Cup winner's fourth gold medal in a major event after her slalom world title in 2009 and her super-combined and slalom victories at the Vancouver Olympics in 2010.
Victory was all the sweeter as she beat the best skier of the winter, Maze, who was crowned in Tuesday's super-G but had to settle for silver this time, and defending champion Fenninger.
Austrian Fenninger had shared the lead with Maze after the first run but straddled a gate early in the slalom and went out.
"I really didn't expect this," Hoefl-Riesch told reporters. "Even after the downhill, I was going for second behind Tina given her level in slalom this season. When I saw that she was behind me, it took a while to sink in especially as I essentially skied a controlled slalom, trying not to go out."
Maze, who missed her second world title of the week by 0.46 seconds, was possibly hampered by a sudden drop in visibility when she tackled the slalom leg.
Too conservative in the afternoon, the Slovenian was bitterly disappointed to finish second.
"I cannot be happy with the way I handled the slalom. I was too laid back, too respectful. I had a lot of pressure and tension and I was unable to relax," the World Cup leader said.
"I'm glad to get a medal but I was hoping for more. There are still a lot of races ahead."
Veteran Nicole Hosp gave the host country their first medal in the competition with the bronze, her seventh medal at world and Olympic level.
The Austrian, hampered by knee injuries since her 2007 World Cup overall title, went full circle, 10 years after her first medal at a world championships, also in the super-combined in St Moritz.
Despite the disappointment for Fenninger, the home team were happy to have four skiers in the top six, with Michaela Kirchgasser, Kathrin Zettel and Elisabeth Goergl finishing just off the podium.
Kirchgasser and Zettel will be among the women to watch in the penultimate day's slalom, boosted by the news that compatriot Marlies Schild, who tore knee ligaments in December, will probably be fit to defend her crown.
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