St. Johnstone upset the odds on Tuesday night with a 3-1 win at Ibrox.
The Gers were favourites ahead of the clash with St. Johnstone, but found their top-flight opponents difficult to contain and bowed out with a 3-1 defeat.
Weir feels the early season lesson could hold them in good stead for the campaign going forward and will be a useful learning experience for his players, after their previously all-conquering start to the season.
"We can do some aspects better, but on the whole, it was a disappointing result. Looking forward though in the big picture, it could be a good thing for us,” Weir told Rangers.co.uk.
"We're 12 games and three months in, and that's our first competitive defeat. It's a new challenge for us and the group, and it's something we haven't encountered before.
"We need to think why it happened, how it happened and learn from it. That's the biggest thing - we need to see what we didn't do well, and what we need to do better in order to ensure it doesn't happen again."
Learning swiftly from their shortcomings against the Saints will be vital if the club are to get back to the pinnacle of Scottish football sooner rather than later.
Their early season form had some commentators claiming they would be capable of challenging for Europe in the Scottish Premiership with their current squad, but Tuesday’s result has rendered those claims wide of the mark.
While the Mark Warburton project has been an initial success, there remains a great deal of work ahead if the Gers are to be competitive at the first time of asking in the top flight next season.