Wow, thanks for such a thoughtful answer. I will look at the other thread you cited.
This is the newer blessing that I found at osb.org/gen/medal.html .
It seems to be an authoritative source, and I think I've seen in printed on leaflets that are sometimes sold with the unblessed medals themselves. Does this seem legitimate to you? I completely understand the thing about the priest thinking you are crazy! ("But really... we're not!").
V. Our help is in the name of the Lord.
R. Who made heaven and earth.
In the name of God the Father + almighty, who made heaven and earth, the seas and all that is in them, I exorcise these medals against the power and attacks of the evil one. May all who use these medals devoutly be blessed with health of soul and body. In the name of the Father + almighty, of the Son + Jesus Christ our Lord, and of the Holy + Spirit the Paraclete, and in the love of the same Lord Jesus Christ who will come on the last day to judge the living and the dead, and the world by fire.
Let us pray. Almighty God, the boundless source of all good things, we humbly ask that, through the intercession of Saint Benedict, you pour out your blessings + upon these medals. May those who use them devoutly and earnestly strive to perform good works be blessed by you with health of soul and body, the grace of a holy life, and remission of the temporal punishment due to sin.
May they also with the help of your merciful love, resist the temptation of the evil one and strive to exercise true charity and justice toward all, so that one day they may appear sinless and holy in your sight. This we ask though Christ our Lord.
The medals are then sprinkled with holy water.
Nihil obstat and Imprimatur, Saint Cloud, 24 April 1980.