Blake died at the age of 52 on Sunday (29May11) after suffering complications from pneumonia.
The popular actor's career was cut short in 1986 when he was involved in a car smash while filming The Lighthorsemen in the South Australian desert, which left him permanently brain-damaged and dependent on his mother Mascot to look after him.
Sweet, who starred alongside Blake in the film and was by his friend's bedside following the accident, found Blake's deterioration "devastating".
He recalls, "We got on very well... we used to sit around and shoot the breeze, and he was very popular with the ladies. (After the accident) we tried anything just to get him to wake up. It was quite devastating."
Another The Lighthorsemen co-star, Peter Phelps, adds, "We had formed a really good friendship in The Lighthorsemen, going up to the hills and to the pub together. There was always some hope that with the mystery of a brain injury there was a chance. I hope there was no pain (in his death)."
Actor Tony Bonner adds, "It's a blessing of some kind that John is not travelling in any more pain. I hope that he is in a peaceful place now."
Blake's funeral will be held later this week (ends05Jun11).