Sacramentals - like a blessed crucifix - are of the same nature as Jesus.
If we could travel back in time with lab equipment, and take x-rays of Jesus, the results would be the same as any other person’s x-ray. The same goes for whatever worldly scientific test we could do.
Yet, we know that Jesus, being God, was not of the same form as the rest of us.
It is very important that all of our sacraments and sacramentals have this same Christ-like nature. They should appear the same as their regular counter parts. Holy water - if put through laboratory testing - should appear the exact same as regular water. If it didn’t, then it would not be in conformity with the nature of Jesus.
When a crucifix is blessed, it is not the same physical crucifix with spirituality sprinkled on top. No. Rather, it has actually changed form.
For the spiritually connected, there will/should be experiences where holy water - or whatever other sacramental - did bring about a supernatural effect. This is also in keeping with the nature of Jesus. We know that Jesus would, at times, perform miracles. Not always, but it would happen at times.
In the case of the Eucharist, after the priest has consecrated the bread and wine, it also changes form. It becomes the body and blood, soul and divinity of Christ. It is very important that the host in the species of bread would test out to be physical bread in every type of test (same for the species of wine). And, you may know that miracles happen from time to time when the Eucharist has a supernatural event associated with it.
For people that believe in “magical items”, as I understand them, those items possess power in and of themselves apart from God. Sacramentals, however, create a connection with God - and any supernatural affect is due to a relational experience with God.
With both the sacraments and sacramentals, it is about a relationship with God.