Weaver was born and raised in Spokane, Washington and attended Gonzaga Preparatory School, where he played baseball and football. He was named first team All-State and the Inland Northwest Defensive MVP after making 123 tackles, 36 for a loss, with 14 sacks and six forced fumbles. Rated a three-star prospect by most recruiting services, Weaver committed to play college football at California over offers from Arizona, Boise State, Utah, Washington and Washington State. As a senior, Weaver was named the State Defensive Player of the Year after recording 125 tackles, 1 int, 5 forced fumbles, 37 tackles for loss, 24 sacks, and two safeties. He finished high school career with 393 tackles, 78.0 tackles for loss, 45.0 sacks, and 14 forced fumbles.
College career
Weaver played in 11 games as a true freshman as a reserve defensive end, making 16 tackles with 1.5 sacks. Weaver moved from defensive end to outside linebacker during spring camp and then moved to inside linebacker going into his sophomore year. He became a starter midway through the season and finished with 55 tackles, two for loss, and two passes broken up. As a junior, Weaver started all 13 of the Golden Bears games and led the FBS with 159 tackles with 4.5 sacks, two interceptions, and six passes broken up. He was named the Pac-12 Conferenceplayer of the week on October 29, 2018 for an 11-tackle performance with a pass broken up and an interception return for a touchdown in Cal's 12-10 upset of #15 Washington. Weaver was named a second team All-American by Pro Football Focus, first team All-Pac-12 by the Associated Press and second team All-Pac-12 by the league's coaches. Weaver entered his senior season on the watchlists for the Butkus Award and the Bronko Nagurski Trophy. He was named a midseason All-American by the Associated Press and CBS Sports. At the end of the season, Weaver was named the Pac-12 Defensive Player of the Year and earned first-team All-Pac-12 honors after leading the nation with a school-record and Pac-12-record 182 tackles. He also became the first Cal player to earn consensus first-team All-American honors since Daymeion Hughes and DeSean Jackson in 2006.
Professional career
Weaver was drafted by the Arizona Cardinals in the sixth round with the 202nd overall pick of the 2020 NFL Draft.
