Arteta thought it all out very well, they played great in defense and used all their attacking opportunities perfectly, I didn't expect Arsenal to beat Real away, but Real's defensive problems are now clearly evident and in the return match they should have been more involved in attacking, so there were gaps in defense, more space for Arsenal's attacking players. Mbappe thought that with Real he had a better chance of winning the Champions League, but Real is already out, and PSG is in the semi-finals.)
Arsenal with Arteta management are no longer too naive like they were in the past with so much obession on attacking. In two latest seasons, they have been playing with quite good balance between attacking and defense systems and they actually build up their tactics and strategy on defense system. It's nothing wrong rather than good because if you don't let your opponent scoring a goal, you won't lose a match except if you make an own conceded goal. Then with solid defense, if you can score goal, you have very high chance to win a match.
Transporting to Madrid and Bernabeu stadium with main task is securing three goal advantage, Arsenal played well in defense, and they patiently waited for opportunities for dangerous counter attacks and eventually having two goals for beating Real Madrid in Bernabeu stadium.
Now they are on a road to the final match, only two more semi final matches and their opponent is PSG. It's interesting that both PSG and Arsenal have never won any UEFA Champions League title.