He attained the rank of major general and was prominent for serving in several United States Army Air Forces command positions during World War II.

At the beginning of World War I Weaver transferred to the Aviation Section of the Signal Corps, and was initially assigned as Commandant of Flying Cadets at Wilbur Wright Field, Ohio, receiving promotion to major.

While en route, he learned that 500 students were already traveling to the site, but that the school was being formed so quickly that there were no plans for housing, feeding or instructional facilities.

Within two days, he had secured the use of a Willys-Overland factory building via a verbal agreement with the company president, cleared the site of over 3,000 stored automobiles using volunteer labor, and supervised the installation of bunks, classrooms and mess halls.

He continued in command until the end of the war, and supervised the education of thousands of soldiers who served as airplane mechanics in the United States and Europe.

Weaver supervised an overhaul, and within a year, buildings had been repaired, hangars had floors installed, and aircraft parking ramps and aprons had been paved.

As part of his effort to create basic training centers and officer candidate schools for new recruits, Weaver arranged for the use of resort hotels in Atlantic City, Miami Beach, St. Petersburg, and Chicago, arguing successfully that these facilities, then being underused because people were unable to take vacations during the war, were the only ones that were vacant and large enough for the needs of the military.

In July 1943 Weaver's health began to fail as the result of overexertion required by his wartime command, and he was retired for physical disability.