Where Leinster usually have two players lift the trophy after a win, it was left to O’Brien to take on that honour alone after the success against Glasgow.
The Leinster, Ireland and Lions flanker will leave Dublin after more than a decade of service when he joins London Irish next term.
And although injury denied O’Brien a final appearance as a player, Leinster skipper Johnny Sexton explained why it was so important to give him the ultimate honour of lifting the trophy.
Sexton said: “Yeah, we knew early enough in the week that Seany was struggling a little bit.
“And we wanted to make sure his last contribution wasn’t Saracens.
“His last memory now will be lifting the trophy, there’s not too many people who have lifted the trophy by themselves in Leinster. It’s guys like Leo (Cullen) and Isa (Nacewa), they’re the only two. The rest of the time we always do it in twos.
“It was fitting for him, we’re really going to miss him. I’m going to miss him.
“To be fair, he’s one of the best players I’ve ever played with. As a forward, I’d say he’s the best. No offence to Leo.
“Just, other forwards in the world didn’t have his drive, as a leader and a player we’re going to miss him.
“Obviously, we drive things from within and make sure the younger players coming through are driving it.”
While O’Brien was not on the pitch in the 18-15 victory over Glasgow Warriors, it was a success built in his image as Leinster showed their resilient side to record victory.
In damp conditions, it was never going to be possible to play the all-court game of which both these sides are capable.
And in what became an arm wrestle in front of a record crowd for a Guinness PRO14 final, Leinster showed that they had learned the lessons from their European defeat to Saracens.
Sexton added: “I’m very proud of the lads.
“The way we bounced back after what was probably the lowest point of all our careers really in terms of losing a European Cup final.”