And Borders chief executive Alastair Cranston has urged the Borders public to show their gratitude and support for two Scottish rugby legends by turning out in full force on Friday.
Armstrong, the 37-year old scrum half who made his Scotland debut in 1988, went on to earn 51 caps before retiring from international rugby in 1999 to concentrate on a club career that has lasted even longer than Armstrong imagined.
He returned to the Borders two years ago, captaining Scotland's new professional side in their first year before spending much of this season as understudy to Scotland international Chris Cusiter. When he has played, he proved still to be an inspiration both to team mates and supporters.
Alastair Cranston paid tribute to the contribution both Armstrong and Weir have made to the Borders. He said: "To have had two players of such stature at the club has been a tremendous boost for us all, especially the younger players waiting to come through the ranks and the community in general. They have both come full circle in their careers having left the Borders some years ago to then return and make a massive contribution to this club, a good example that I hope others will follow.
"Being realistic, this is just a stage that all pro-clubs in Scotland will go through at some point. We must take stock and now move on for the benefit of the club's future."
Scotland's Director of Rugby, Ian McGeechan, paid tribute to Armstrong: "The first time I was involved with Gary was when he played for the Scotland B team against Italy in 1988. It's fair to say he exploded onto the scene.
"I would rate him not just as one of the best players to play for Scotland but as one of the best ever people to represent his country. I wish I could have bottled what he has got and put it into every player that pulls on a Scotland jersey.
"He has had a phenomenal career. He has led by example, both on the match field and in training. Those who have played with him would rate him as highly as any scrum-half in the world. Pound for pound he was probably the bravest player to play for Scotland and any coach would have wanted him from any era or any generation to have worn the thistle."
"Friday will be my last game," confirmed Armstrong this week. "My career has probably lasted longer than most people's, but this was always going to be my last team and I was very lucky to get these two years with The Borders. I always said I wanted to finish my career in the Borders, so it's been a good experience."
There were tears when Armstrong bowed out of international rugby following the 1999 World Cup game against the All Blacks at Murrayfield, and he anticipates the same on Friday at Netherdale. "I'm always a wee bit emotional," said Armstrong. "It's hard to say goodbye to people you've worked closely with, but I've had eight years as a professional and I really think I've had the best of both worlds, having played for a long time as an amateur and then as the game went professional.
"I'll continue to follow The Borders and I wish them well. The first year with the team was really good, while this year was more difficult in terms of trying to compete in the Celtic League. We struggled, and that's frustrating because you want to be competing and winning. To be competitive we just needed more quality players - it's as simple as that.
"Now it's back to the real world and I intend to concentrate on my business. I bought a small haulage company in Jedburgh a few weeks ago and I'm looking forward to the challenge of that. It's a new chapter in my life, and it's exciting.
"I don't know if I'll return to rugby. You never say never, and perhaps I'll get involved in coaching somewhere down the line, but my priority now is my business."