I was given a rosary that was blessed by John Paul the II. A family member gave it to me who is not Catholic but obtained the Rosary in Italy many years ago. Since it was blessed by a Saint, is it more special or should it be treated different? Or is it just a nice item that I own?
yes - the things I have that were blessed by him - were blessed by a Pope and a Saint.
I assume he did not buy it after the blessing but it was given to him or he bought it and it was then blessed. If so there is also a plenary indulgence on the feast of St. Peter and St. Paul (under the usual conditions for such…Holy Communion, confession, prayer for the Pope, detachment from all sin).
From the document on Indulgences:
Use of Articles of Devotion. (Verbatim follows

"The faithful, who devoutly use an article of devotion (crucifix or cross, rosary, scapular or medal) properly blessed by any priest, obtain a partial indulgence. “But if the article of devotion has been blessed by the Sovereign Pontiff or by any Bishop, the faithful, using it, can also gain a PLENARY INDULGENCE on the feast of the Holy Apostles, Peter and Paul, provided they also make a profession of faith according to any legitimate formula.”