Blessed salt is an instrument of grace to preserve one from the
corruption of evil occurring as sin, sickness, demonic influence, etc.
As in the case of all sacramentals, its power comes not from the sign
itself, but by means of the Church's official (liturgical, not private)
prayer of blessing -- a power the Church derives from Christ Himself.
(see Matt. 16:19 and 18:18). As the Vatican II document on the Liturgy
states, both Sacraments and sacramentals sanctify us, not of themselves,
but by power flowing from the redemptive act of Jesus, elicited by the
Church's intercession to be directed through those external signs and
elements. Hence sacramentals like blessed salt, holy water, medals,
etc., are not to be used superstitiously as having self-contained power,
but as 'focus points' funneling one's faith toward Jesus, just as a
flag is used as a focus point of patriotism, or as handkerchiefs were
used to focus faith for healing and deliverance (Acts 19:12).
Thus, used non-superstitiously, modest amounts of blessed salt may be
sprinkled in one's bedroom, or across thresholds to prevent burglary, in
cars for safety, etc. A few grains of blessed salt in drinking water
or used in cooking or as food seasoning often bring astonishing
spiritual and physical benefits. As with the use of Sacraments, much
depends on the faith and devotion of the person using salt or any
sacramental. This faith must be Jesus-centered, as was the faith of the
blind man in John 9; he had faith in Jesus, not in the mud and spittle
used by Jesus to heal him.
See actual remains here
Read more about incorrupt saints here
The symbolic importance of water is ancient, and its ritual use can
be found in the Old Testament, where it was used for purifying rites
privately and liturgically. It is also a sign of God’s creative power (Genesis 1:2), a metaphor for Jehovah as the source of life spiritually (Isaiah 55:1-2), and it is used as an agent of healing (2 King’s 5:10).
There are also many Old Testament types of water’s significance in the
New Testament, such as Pharaoh’s army (sin) being drowned in the sea
(the waters of baptism, Exodus 14:28).
In the New Testament, water takes on even greater significance in its
connection with Christ, who identifies himself with the Living Water (John 7:37-39).
Baptism in water is also declared as necessary for our salvation, as
Jesus himself said, “unless a man be born of water and the Holy Ghost”
he cannot be saved (John 3:5).
The Blood of St. Januarius
(Sept 19) - St. Januarius was thrown into a fiery furnace, but that the flames would not touch him. Afterwards, the saint and his companions were exposed to wild beasts, but without any effect. Timotheus, declaring that this was due to magic, ordered the martyrs to be beheaded. He was smitten with blindness, but Januarius cured him and 5,000 were converted to Christ before the marytrs were decapitated. Seventeen hundred years later, when the blood is brought in contact with the relic of his head, the blood liquifies and sometimes bubbles. It is know that in times when the blood does not liquify, disaster will follow.
The Girdle of Thomas
The Girdle of Thomas, Virgin's Girdle, Holy Belt, or Sacra Cintola. A Christian form of a 'girdle' or knotted textile cord used as a belt, that according to a medieval legend was dropped by the Virgin Mary from the sky to Saint Thomas the Apostle at or around the time of the Assumption of Mary to heaven. The relic is kept at the Prato Cathedral in Tuscany, Italy. The story was depicted in art in Florence and Tuscany.