Weaver graduated from the School of the Art Institute of Chicago in 1946, where he studied with Albin Polasek and Emil Zettler.
He was known for creating a statue of Charles Marion Russell at the National Statuary Hall Collection, and three busts of Chester West. Nimitz for the United States Navy. He received a teaching position in sculpture and figure drawing at the Layton School of Art in Milwaukee where he taught from 1946 to 1951. He was a curator for the Montana Historical Society for five years.
He worked as a Natural History Sculptor for the Smithsonian Institution for six years.
In 1966, he started working with the Alberta Provincial Museum prior to its opening on December 6, 1967. He became a Canadian citizen in 1973.
Weaver died of a heart attack at the age of 92 on April 12, 2013 at his home of many years in Silver Creek, British Columbia.
On March 28, 2010, Weaver"s 90th birthday, the House of Representatives and Senate both stopped proceedings to give the sculptor a standing ovation as well as singing happy birthday.