Ferguson was among the speakers during a memorial service for the former Rangers, Everton and Scotland manager, who died on October 26 at the age of 73 following a three-year battle with cancer.
A private funeral had been held earlier this month for Smith, who won 21 trophies as Rangers manager, and the Glasgow Cathedral service allowed a number of people from the world of football to pay their respects.
Ferguson recalled how he first noticed Smith's coaching talents during a course at Largs in 1972.
"Imagination, control of the session, he was a certainty to make it," the former Rangers player said.
Smith began his coaching career with Dundee United and Ferguson told how he failed to prise Smith away from Jim McLean. But he later briefly employed Smith as his assistant with Scotland and Manchester United.
Ferguson told how Smith refereed training games and would take a lax approach to challenges on Ronaldo, who "came with all the tricks in the world and wanted to beat all the players".
"He walked up to me and says 'Boss, do they not have fouls in Scotland?' And he learned. He learned how to pass the ball and he can thank Walter for that. No question."
Summing up, Ferguson borrowed a phrase used earlier by Smith's younger brother, Ian.
"I was looking for a word that encapsulates this man and it's definitely giant," he said.
Ally McCoist relayed the attributes of his mentor.
"He was loyal, he was caring, he was considerate, he was honest, he was hard-working, he was unbelievably friendly, he just put you at ease, and an absolutely wicked sense of humour," the former Rangers player and manager said.
McCoist stressed that Smith's legacy was his immediate family - wife Ethel, sons Neil and Steven and seven grandchildren.
He quoted a line from American civil rights poet Maya Angelou, who stated: "People may forget what you said, people may forget what you did, but people will never forget how you made them feel."
McCoist added: "I don't think I will ever forget what Walter did. I don't think I will ever forget what Walter said. But I can guarantee you that I will never, ever, ever, ever forget how that man made us all feel."
Smith's son, Neil, earlier gave an insight into the family man.
"One of my abiding memories of my dad is him sitting in a chair at home trying to peacefully watch a game on TV with his six grandsons circled around him bombarding him with football questions for the 90 minutes," he said.
"At half-time he would get dragged out of his seat to go in imaginary goals as the boys fired shots at him while he tried doing everything he could to stop my mum's vases or the window blinds being smashed to smithereens."
After his father had watched his twin sons winning a game of football 4-3 after being four up at half-time, he recounted his words to his grandchildren: "Great result today boys but you maybe could have worked a bit harder in the second half and the team could have kept its shape and kept the ball a bit better.
"My boys were only six years old and were playing five-a-side," he added. "They found out pretty quickly it would be hard to impress their papa."
Former Rangers director John Gilligan outlined how Smith had remained "the same very personable Walter" throughout all of his success at Ibrox.
"Superstars, cleaners, workers, it never mattered to Walter," he added. "He seemed to float through Ibrox and everyone was important."
Rangers players past and present attended the service with the many former stars including Derek McInnes, Andy Goram, Charlie Miller, Trevor Steven, Nigel Spackman, Richard Gough, Sasa Papac, Stuart McCall, Nikica Jelavic and Duncan Ferguson.
Coaching colleagues also included Archie Knox, Ian Durrant, Jim Stewart and Kenny McDowall.
Former Celtic managers Davie Hay, Gordon Strachan and Neil Lennon attended alongside former skipper Roy Aitken and present and recent chief executives Michael Nicholson and Peter Lawwell.
A contingent from Dundee United, where Smith spent most of his playing days and began his coaching career, included Paul Hegarty, Maurice Malpas, Hamish McAlpine and Davie Dodds.
Other football personalities included Darren Fletcher, Mark Hughes, Frank Lampard, Eddie Gray, Craig Levein, Craig Brown and Brechin manager Dick Campbell, Smith's long-term friend.
Representatives from the Scottish football authorities were there as well as Hearts manager Robbie Neilson and Motherwell boss Graham Alexander, both of whom played under Smith for Scotland.