just wish people wouldn't keep carping on about it........

when you say tiny fishing weights, are you referring to what anglers call 'split-shot' - those 2 - 3 mm. dia. balls, that once were made of lead, but now are required by law, I think, to be made from another less toxic metal?? ............ or did you mean something completely different

For enclosed cavities such as decanters, there is a proprietary product called 'Magic Balls' (or at least there used to be) - small 'shot' shaped steel balls covered in copper, which can be used inside the glass - with some form of liquid metal polish such as Brasso - and then shaken for some minutes. But this product will obviously not repair damage to the surface of the glass, and is intended to remove light staining only.
If you read the old posts, there was much talk of using flexible drives powered by an electric drill, and felt discs and cerium/aluminium oxide etc.
On external curved surfaces, care is needed to avoid putting 'flats' on surfaces, if too much rubbing is applied.
Unless the water staining is light, I always found it frustrating not being able to repair the surface properly, and of course there's always the problem - especially on internal surfaces - that after the scale has been removed, the glass will prove to be damaged and beyond amateur repair.
Appreciate this all sounds very pessimistic, but so often we spend a long time working on a piece of glass, then washing and drying it, only to find it still remains cloudy.