The Frenchman’s fine display came just a week after he missed two golden chances in the first leg of the quarter-final with Slavia, which Arsenal drew 1-1 at Emirates Stadium.
Since then Lacazette, who will have one year left on his contract in the summer, has bounced back and his two goals on Thursday followed on from a brace at Sheffield United last Sunday.
“In key moments and in big matches, you need players – and senior players who have this experience – to make the difference for you,” Arteta said.
“For me, in his style and in his development, even if he’s soon turning 30 years old, he’s on the right path because he’s very willing to learn.
“He’s doing things in a much better way than before. He really glues the team together and that’s a quality that is not easy for a striker. He’s got it.”
Lacazette endured a tough night last week in the first leg against Slavia, hitting the bar when one-on-one with the goalkeeper.
He was excellent in Prague on Thursday, though, slotting home a penalty and grabbing another goal in the second half.
“It shows the personality that Laca has. He missed two big chances in the home game and then you have to see a reaction,” said Arteta.
“That reaction could be with some fear, some doubt or feeling a little bit guilty.
“Or the other one is to have a strong personality and to react, to say: ‘Now I’m going to put them in the back of the net’.
“He’s done that in two games consecutively, being really, really efficient. Then his momentum continues, the form that he’s in continues and it’s really important for the team.”