The Ivory Coast international, sent off for a head-butt on Leeds United’s Ezgjan Alioski that Arteta called unacceptable last weekend, produced a fine finish in the 50th minute, shortly after striking the crossbar with a superb curling effort.
Arsenal, disappointing in a drab first half against the Norwegian side they beat 4-1 at home, doubled their lead five minutes later when Reiss Nelson converted a precise low cross.
Substitute Folarin Balogun, 19, made it 3-0 to the visitors with his first goal for the club, moments after coming on, silencing the smattering of home fans allowed inside the stadium.
Arsenal’s win left them top of Group B with a maximum 12 points from four games, six clear of second-placed Molde. Rapid Vienna, who have three points, face Dundalk later.