Arsenal managed to do one thing against Sheffield United that they have never pulled off away from home in the Premier League before. By the time the half-time whistle blew at Bramall Lane on Monday evening, Arsenal were already 5-0 up against Sheffield United. On top of that, in the first-half, Mikel Arteta also reached a personal landmark. As Arsenal put the Blades to the sword, they scored the 300th Premier League goal of Arteta’s reign. It was a dazzling first 45 minutes from the Gunners, and they pulled Chris Wilder’s side apart. Martin Odegaard, Gabriel Martinelli, Kai Havertz, and Decla…