Watson, who will join St George Illawarra next season before heading to the PNG Chiefs, was denied the chance to sign off with a premiership after he was ruled out of the grand final win over Newcastle due to concussion.
The Roosters attempted to seek clearance from the NRL to allow Watson to play but had their request denied because the 30-year-old's head knock in the preliminary final fell inside the 11-day standdown period.
Robinson was keen to ensure that Watson didn't leave Moore Park without a memento and gave the fan favourite his ring inscribed with the word "coach".
"In 30 years' time, when I've got grandkids, I'll be telling them that I've coached the Sydney Roosters," Watson said.
Beniah Ioelu - the hooker who replaced Watson in the Roosters' gameday squad - offered his senior teammate his ring.
But Watson declined, having already acquired the one given to Robinson, who gave him his NRL debut way back in 2016.
"Me and Trent have always had a good relationship, he's been instrumental in my career; giving me a shot, and then the last few years making me develop into the player I am today," said Watson, who has played 127 games for the Roosters across two stints.
"I wouldn't be the person I am without this club."
Watson became the first player to miss a grand final as a result of concussion and held no ill feeling about the decision, which was handed down to him on Friday.
Watson said he had a few hours to feel sorry for himself before focusing his energy on supporting Ioelu, who did not get on the field, to prepare as best he could.
"It's a lifetime of work. From (being) a kid, you've dreamt of this moment, and then 11 years of playing NRL, and you get your first opportunity in a grand final," Watson said.
"Then you get ruled out. It's disappointing, I'm not gonna lie I was gutted.
"But at the end of the day, the situation is what it is, you can't change it, so the show goes on."
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