Judge Schroeder dismissed "possession of a dangerous weapon by an underage person," something that Rittenhouse himself admitted to on the stand.
Schroder made his ruling due to a technicality about the length of the barrel on the AR15, the gun Rittenhouse used to shoot three people, killing two.
If that's not a dangerous weapon I don't know what is.
The Washington Post reports, "The misdemeanor weapons charge prohibits minors from possessing a firearm with exceptions for hunting and carries a maximum sentence of up to nine months in jail or up to a $10,000 fine. The jury will render a verdict on the five remaining counts, all related to homicide charges or reckless endangerment."
Also Wapo: "There is no dispute that Rittenhouse was 17 when he carried an AR-style semi-automatic rifle on the streets of Kenosha and used it. But the defense argued that Wisconsin law had an exception that could be read to clear Rittenhouse. After prosecutors conceded on Monday that Rittenhouse’s rifle was not short-barreled, Judge Bruce Schroeder dismissed the charge."