STAMFORD-A Norwalk man pleaded guilty to stabbing another man several times in front of a South Norwalk bar last October. Mykell Mitchell, 25, pleaded guilty to a charge of first-degree assault Tuesday at the Stamford courthouse. As part of a plea agreement worked out with Supervisory Assistant State’s Attorney James Bernardi, Mitchell will be sentenced to three and one-half years in jail when he returns to court on Nov.