According to Adam Silver, in determining the penalty to be slapped on Ja Morant, the NBA looked at the history of prior/similar acts and Morant's own history as a player.
In terms of prior/similar acts committed by other players, Gilbert Arenas's case (possession of guns in the team dugout) would be the extreme case. He was suspended for the rest of the 2009-10 season after investigations were concluded in January 2010. In 2021, the NBA suspended Malik Beasley for 12 games for a gun-related incident off-court that led, however, to felony charges (threatening to commit a crime of violence).
Morant was suspended for eight games for his first infraction in March. Most likely the NBA will more than double his next suspension since he is a repeat offender, even if his second infraction was not illegal in itself. Wild guess, but I think it will be around 20 games (or a fourth of the season).