What Rome gave a soldier at the end: his name in writing, and a piece of land
Yours comes with both, in the same spirit: your name on the certificate, and a souvenir plot of Italian land in Sicily.
Modelled on a real Roman diploma
When a soldier of the auxilia finished his service, Rome set down his name, his unit and his discharge in a diploma like this one, and granted him citizenship. Real ones survive; the Met has this one on view in New York. See it on the Met's website. Your certificate takes up the same form and says so at its head, Diploma Honorarivm, an honorary diploma: drawn to one name, sealed with the eagle and numbered so that no two are alike. It is a keepsake in that spirit, and grants nothing.
Sealed with his eagle, signed with his title
The aquilifer carried the legion's eagle, the one thing a legion could never lose. That eagle is the seal at the head of your certificate, and his title closes it, above the signature: Pro Legione X · Aquilifer. The story of the eagle.
And the land
A legionary who served out his years was owed the praemia, a discharge settlement of land or of cash. Caesar had the veterans of the Tenth settled at Narbo in Gaul, a colony that carried their name: Narbo Martius Decumanorum, of the men of the Tenth. Yours is a souvenir plot in Sicily, Rome's first province, in the hills above the Ionian Sea north of Taormina, dedicated in the name on your certificate.
A keepsake, not a deed, and not military service.