Blacks are shot less than what is commensurate with their criminal and violent behavior. Blacks being 13% of the American population commit around 50% of the homicides; the top marker for all violent behavior. In other words violence builds up to homicide and it stands to reason Blacks lead in all underlying violence. Criminality is also at issue and is reflected in the High volume of 911 calls received in predominantly black communities.
Blake confessed to having the knife when he was shot.
You're right the absence of charges, if true, comes from the impunity with which the Kenosha DA performs his job. As has become evident nationwide with his televised performance of prosecutorial misconduct in regards to Kyle Rittenhouse. Yet another reason to have the man fired and disbarred.