These single devices, contrary to those promoting them, do nothing to correct or stabalize an imbalanced immune system or terrain
Wrong - those single devices destroy pathogens and boost the immune system to enable the body to heal itself and become balanced again. You might take a better look around and see that some of those who are promoting them also promote the idea of embracing a healthy lifestyle, diet and nutrition. If one does not do that, then I will agree with you that such devices are used more like allopathic medicine - and the same would be true for any number of herbs, including those in say, a liver tonic.
Even so, unlike allopathic medicine, there has been no observed serious side effect from either silver or oleander when properly prepared and administered.