Cardiff also clawed their way to a 26-17 win but there was no denying that this was Humphreys' night, along with players who are moving on from Ulster this summer, which include Tommy Bowe, Roger Wilson, Justin Harrison, Mark Bartholomeusz and Neil Best.
Ronan O'Gara enjoyed a ding dong battle with Humphreys for the Ireland number 10 jersey, which brought back memories back of the Ollie Campbell-Tony Ward out-half rivalry during the amateur era.
Both men had their spells of dominance in the position, with Humphreys most notably starting the 2003 World Cup as first choice.
But as the years went on and O'Gara came to the fore, the Ballymena man, who won 72 Ireland caps, bowed out from the Test arena in 2006 after ten years in the squad.
Celebrating the career of his great rival and friend, O'Gara said: "Obviously I've known David for many years, both as an opponent when we played for our respective provinces and as a colleague with Ireland. I would have the highest regard for him, both as a player and a sportsman.
"We've vied for the same number Ireland jersey and when this went my way, he was always supportive though doubtless disappointed himself.
Humphreys, who captained Ireland five times, made an immense contribution to Ulster and Irish rugby, particularly when you consider he scored a stunning 1,585 points for his province and a one-time record 560 points for his country.
Hailing him as 'an outstanding ambassador for Ulster rugby', current Ireland captain Brian O'Driscoll said: "David has been an outstanding ambassador for Ulster rugby since making his debut and was an influential figure as the province went on to lift both the European Cup and Celtic League trophies in recent years.
"I had the pleasure in playing outside David for many years for Ireland and he was a composed presence throughout and was an integral part of the national team's success in a competitive area of the squad.
"He should be very proud of his achievements and I would like to wish him and his family the very best of luck in the future."