The 32-year-old Frenchman scored a record 226 goals during his eight-year stay in North London, winning two Premier League titles and three FA Cups with the Gunners.
However, he has not enjoyed as successful a spell in the colours of the Catalans - despite netting 34 goals in 74 La Liga appearances - with the former Monaco and Juventus man drifting in and out of the side under Pep Guardiola's guidance.
Henry will make an emotional return to Emirates Stadium on Wednesday for the first time as an opposing player since departing in 2007.
And although Gunners boss Wenger believes the Arsenal idol will get the rapturous welcome that he deserves, all niceties will end during the 90 minutes of play on the pitch.
"He is still a threat because he is an exceptional talent. [He is a] very intelligent talent as well," Wenger said ahead of the last eight encounter.
"We are happy to see him back at the Emirates and he will get the warm welcome that he deserves. And when the game starts it will be a quarter-final of the Champions League where we will of course give everything to beat him."
Henry himself admitted he was unsure how the Arsenal fans will react upon his return 'home' on Wednesday.
“Since I joined Barcelona I have only been back to Arsenal on one occasion. I do not know how people will react. I have a special relationship with Arsenal fans. They are great. Incredible. They always support you and help the team," he said in the Express.
“I am now an Arsenal supporter. I will always be one. When Arsenal play and I can see the game, you can be sure to find me in front of a television."
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