Let's see if things will work out as you said; if not, Arsenal winning against PSG at home is going to be a difficult thing to happen, although it's football, and I’m also hoping to see that happen. Just that I’m curious because we already saw what happened at Arsenal's home when PSG came; they failed to utilise the advantage of being at home to win against PSG.
That’s why I’m wondering how difficult the second leg will be for them. You are right; since they won against Real Madrid, they have confidence. Instead of using the same energy for PSG, they failed because, obviously, things did not go as they played against Real Madrid.
This is a different condition because even though Arsenal managed to beat Real Madrid as one of the most successful clubs in the Champions League, it doesn't necessarily mean they can beat other teams easily. The euphoria of winning against Real Madrid made Arsenal complacent and didn't take advantage of the conditions well enough when facing PSG so they had to accept defeat at home.
On the other hand PSG continued to improve and they took advantage of every little opportunity that existed so that they managed to beat Arsenal. Playing at home will certainly be quite advantageous for PSG because I am sure their motivation will be much greater to get the win.