The scoreline was flattering for Arsenal, which ended a three-game Premier League losing streak, but Watford only had itself to blame after spurning multiple chances, most notably captain Troy Deeney's tame penalty.
That was a positive, as was Mesut Ozil's record for becoming the fastest player in Premier League history to reach 50 assists.
When Arsenal met Watford earlier on in the campaign, it was a disaster for the North London side. Patrick van Aanholt pulled one back for the visitors.
"I can not say anything more, because there is nothing to say and I do not want to hurt Arsene, whom I adore and for whom I have a lot of respect".
"Sometimes you just go and you have that feeling and today I felt it".
Mkhitaryan sealed Arsenal's victory, their first league win since beating Everton 5-1 on 3 February, with a shot from inside the penalty area following Aubameyang's pass.