Only Fraser Brown, Richie Gray and Sean Kennedy are older than 32-year-old Weir, who has started three games and come off the bench six times in this season's campaign
Speaking to BBC Scotland, Weir said: "I know now my role as an elder statesman in the squad. The starts won't be frequent, but I've still got a big job to do - coming off the bench and calming down the boys when things are going a bit hairy, or changing the game wherever I see fit.
"Physically I feel in really good shape and I'm really looking forward to doing something special with the last 14 weeks of the season."
Weir has been impressed by head coach Franco Smith since the South African took charge two years ago.
"This season has been a real squad effort," he said. Last year Franco came in and wanted to implement his changes and make sure we were successful on the pitch.
"Now we're into his second season, we know what he wants and how he wants the game played."
Weir is out of contract at the end of the season, and with Adam Hastings rumoured to be returning to Scotstoun, it looked like Weir may be playing his rugby elsewhere after the summer. However, Weir told The Offside Line that he is close to extending his deal.
"I'm out of contract in the summer but things are looking positive to keep playing. It's pretty much done. It's looking likely that I'll be staying here. I've just left my agent to deal with all that nonsense and told them to come to me when they've got something worthwhile to tell me! The communication has all been good and it's all looking pretty cushty.
"I've really enjoyed this season. I feel that every time I've taken the pitch alongside other guys getting their chances we've taken them. I feel comfortable slotting in now. I'm at an age where I want to know the gameplan first and then it's how can I implement that.
"We're all comfortable with what Franco is asking us and have a knowledge of what each other is doing."