I believe you are incorrect. Where is the proof of the exeption in your case. Canaon law clearly says that layman may not possess first class relics.
If you got your object off of the internet perhaps it isn’t genuine. The relics on the internet are mostly frauds and if by some chance they are genuine they should be given to the competant authorities.
There is nothing in Canon law that forbids laymen to possess first class relics.
Can. 1186 To foster the sanctification of the people of God, the Church commends to the special and filial veneration of Christ’s faithful the Blessed Mary ever-Virgin, the Mother of God, whom Christ constituted the Mother of all. The Church also promotes the true and authentic cult of the other Saints, by whose example the faithful are edified and by whose intercession they are supported.
Can. 1187 Only those servants of God may be venerated by public cult who have been numbered by ecclesiastical authority among the Saints or the Blessed.
Can. 1188 The practice of exposing sacred images in churches for the veneration of the faithful is to be retained. However, these images are to be displayed in moderate numbers and in suitable fashion, so that the christian people are not disturbed, nor is occasion given for less than appropriate devotion.
Can. 1189 The written permission of the Ordinary is required to restore precious images needing repair: that is, those distinguished by reason of age, art or cult, which are exposed in churches and oratories to the veneration of the faithful. Before giving such permission, the Ordinary is to seek the advice of experts.
Can. 1190 §1 It is absolutely wrong to sell sacred relics.
§2 Distinguished relics, and others which are held in great veneration by the people, may not validly be in any way alienated nor transferred on a permanent basis, without the permission of the Apostolic See.