Interesting. Some info from the Wiki:
He is the patron saint of hunters, mathematicians, opticians, and metalworkers.
Hubert's wife died giving birth to their son Floribert, and his grief prompted him to retreat from the court. He withdrew into the forests of the Ardennes and gave himself up entirely to hunting.
Hubert is honored among sport hunters as the originator of ethical hunting behavior. In some versions of the story, the stag is said to have lectured Hubert to hold animals in higher regard and have compassion for them as God's creatures with value in their own right. For example, the hunter ought to only shoot when a clean, quick, and therefore humane kill is assured. He ought to shoot only old stags which are past their prime breeding years and forego a much-anticipated shot on a trophy to instead euthanize a sick or injured animal that might appear on the scene. Further, one ought never to shoot a female with young in tow, to assure the young deer have a mother to guide them to food during the winter. Such is the legacy of Hubert, which is still taught today and who held in high regard in the extensive, rigorous German and Austrian hunter education courses.