Religions have many symbols besides their main holy symbol, each for their own special purpose. The bread that is the body of Christ is an example of such a blessed symbol that must be carefully guarded. Many good religions will use blessed holy water; water is the symbol of life.
Relics are blessed by virtue of their existence. They are individual items that cannot be reproduced. The shroud of Turin is an example of a relic, created from the sweat of a dying avatar and the compassion of one of his most devoted followers. Often the bones or prized belongings of avatars or prophets will be considered relics to a religion. Some relics will have special powers, although they do not have to. Relics are their own treasure.