A man who wore a Ku Klux Klan robe at a Halloween party has been convicted in Concord of attacking two black men while still wearing it several hours later. Witnesses testified that Harold Gallant, 23, and George Harless stabbed the men outside a bar early on Nov. 2. Gallant was found guilty by a Contra Costa County jury of assault with a deadly weapon and intent to inflict bodily harm. Harless pleaded guilty earlier to assault charges and is being held in the California Medical Facility. One of the victims, Tony Hall, 19, was hospitalized for three weeks with stab wounds.