© Getty Images
The Hornets looked the more likely to take the lead early on when Fernando Forestieri's 20-yard shot flashed narrowly wide of Wayne Hennessey's goal.
Davis made the hosts pay for their profligacy in front of goal when his ball to the far post found Byron Webster, who nodded home in first-half stoppage time.
Edwards added to the Hornets misery when he netted a third goal in stoppage time to seal the victory.
The Somerset club are now off the bottom of the Championship, but have a five-point deficit to the sides outside the relegation zone.