If the weights don’t have clips, you could simply sew them in place. The stronger the wind, the heavier weights you’ll need.
One of the most effective solutions if your flag keeps getting twisted around the pole is to replace it. Spinning flag poles have ball bearings inside, so they spin with the flag.
It consists of spinning brackets, which you slide over the pole. As such, it’s a cheaper and easier solution.
Something like canvas is ideal because it’s heavy and weather-resistant. Just bear in mind that it will set you back a bit more in cost.
A flag stabilizer is usually a rigid pole that clips onto the bottom of a flag to stop it from furling. However, you could make your own using a clip, a pole bracket, and a plastic rod.