Eduardo was a surprise name in the Gunners' starting line-up for their FA Cup fourth-round replay - after almost a year out injured - and rewarded his manager with his first goals since scoring against Manchester City in February last year.
Nicklas Bendtner and substitute Robin van Persie also got on the scoresheet as the Gunners brushed aside their Coca-Cola Championship opposition 4-0, making light of the 0-0 stalemate in the initial tie.
"Everybody is very happy for him. This is the kind of game we love to play, and it was good to see them play with the handbrake off," said Wenger.
"He played a big part in that, and I'm very pleased for him.
"He made a big step forward in training two weeks ago, and you could see he found his sharpness in front of goal.
"He's been extremely strong mentally. I've never seen one minute of doubt in his mind, not one minute where he said 'I don't want to do this'.
"He is always wanting more. This guy is small but he has the mental strength of a mountain."
The Frenchman may have to manage the comeback of his Croatian striker carefully - he came off while still in search of his hat-trick with a slight hamstring complaint - but admitted he could yet boost his side's prospects in the end-of-season run-in.
"He had a slight tightness of the hamstring, but we expect it will be a small thing," added Wenger.
"We'll know at the end of the season how important it [his comeback] is, but I'm very happy to have him back. He can play as a striker, on the flank, behind the striker, up front on his own. That is important for us."
Wenger also explained Eduardo's decision to celebrate his second goal, which he earned himself following a second-half surge into the Cardiff box, by running straight to the Arsenal support staff.
"Our fitness coach spent more time with him than with his wife," he joked.
"He deserved that hug, as did the physios and the doctors - they all did a tremendous job. They spent a lot of time with Eduardo.
"We get to use him when he is ready, but they all did a great job with him."
Cardiff boss Dave Jones had less to smile about after a disappointing performance from his team.
"All I can take from tonight is that (goalkeeper) Tom Heaton played very well," he said.
"I'm glad the game is over, because we didn't do ourselves justice tonight whatsoever.
"Sometimes when you come to an Arsenal or one of the big clubs you just have to suffer for 90 minutes - and tonight I think we suffered for 90 minutes.
"We couldn't get any passes away or any control.
"People are telling me we haven't played for two weeks or whatever. But I could look for as many excuses as I want - we just didn't play to the level we are capable of.
"If I could have substituted 10 of them I would have - because we just didn't perform.
"People are saying the Championship is our priority, but it would have been nice to have come here and put in a performance."