Victory was the 42-year-old's first, despite having been a regular feature on the circuit and having been consistently ranked throughout his career.
Riding his London Olympic partner Lunatic, Fredricson to complete a double clear round, as did four other competitors.
Among them was Germany's Marcus Ehning who, despite settling for second, again proved he will be a serious contender at the upcoming European Championships in Denmark.
Dutchman Jeroen Dubbeldam, who is enjoying something of a recent renaissance but is still not guaranteed a place at the Euros, finished third.
In other notable performances, the inexperienced Timothée Anciaume and his nine-year-old stallion Quorioso Pré Noir impressed while not quite challenging the top riders, suggesting a bright future for the Frenchman.