rust removal without scratching?

i have an old metal set of armour that has become rusty through being stored in damp conditions, how can i remove the rust without scratching or damaging the metal

The removed area will be damaged by the rust,

But a metal polish will take off light rust stains.

It really depends on how rusty it is,

is it just like tea stains, then use metal polish

or has the rust taken hold on large areas, as rust treatment may be the only option.

Does Angie clean houses or horses? or just cleans with a hose?