For 26 very powerful symbols go no further than the english alphabet. Ask anyone who is unable to read or write to know the truth of that. Numbers are powerful symbols. Our civilisations and their histories are built on words and numbers.
The crown and the cross are two powerful symbols that need no explanation, their multi level meanings are perceived without need of language. National flags are powerful political symbols which is why they are so often burned. So too are the symbols of military and economic power, the dollar sign, trademarks, uniforms, etc. Symbols are everyday universal language and communication devices.
However, when it’s something religious or esoteric, perhaps a Reiki symbol, its different, magical, special. Or is it?
In one sense these symbols are special, because the mind makes them so. Symbols are devices that impress the mind. It is the mind that interprets and assigns meaning and significance, it is belief that imbues a symbol with power.
That is one of the teachings inherent in symbols, give your power away to something outside yourself and learn that lesson. Realize that the power lies within yourself, and it’s a very different lesson.