Darren Fletcher struck twice, with Wayne Rooney and Nani also getting on the scoresheet during the evening and Ferguson said: "It was a really fantastic performance. The players looked great. They showed tenacity and the passing was terrific.
"They were so disappointed with themselves (after losing 2-1 to Manchester City) on a really important day. I think all the emotions of the week probably caught up with them.
"But today they've made amends for that with a marvellous performance."
United ran the midfield, and Ferguson reserved particular praise for Fletcher, who has had little opportunity to shine this season.
"Darren Fletcher is one of these players who always plays well against Arsenal," he said.
"I think he's had two man of the matches in semi-finals. Sometimes it's horses for courses and I think it was Darren's day.
"Some of the passing was very good and the running off the ball was very good. It was a great performance by us."
Wenger thought Emmanuel Eboue's sending-off in the 49th minute was "harsh" but conceded they had been second best.
However he believes they can rediscover their form against AC Milan in the Champions League on Wednesday.
He said: "It is difficult to find any positives from the performance, apart from the fact we do not have any more injuries.
"Even before the sending off we never looked like we could come back.
"It was difficult. We did not seem the have the physical resources that were needed.
"We were not up to our level. We need to pick ourselves up quickly because we have a massive game on Wednesday and need to be at our best against Milan."