According to Utah law https://le.utah.gov/xcode/Title76/Chapter5/76-5-S102.html
Assault is usually a class B misdemeanor but can be upgraded to class A if the actor causes substantial bodily injury to an individual.
Apparently knocking her unconscious and giving a concussion (symptoms of which she is still suffering from at last public report) is considered "substantial", and increase the max penalties from 6 months in jail to 1 year along with the associated fines, probation, community service, etc.