Vlasis’s name day is February 11, the feast of Blaise.
Churches that follow the Old (Julian) Calendar keep the same feast on February 24 of the civil calendar. See everything commemorated on February 11.
The saint behind the name

Blaise
February 11, Martyr, Βλάσιος
St. Blaise was Bishop of Sebaste in Armenia, a physician of both bodies and souls. During the persecutions of the early fourth century he was seized, and after enduring tortures for his confession of Christ he was beheaded. Tradition tells of his kindness even to wild beasts, and of a boy saved from choking through his prayer.
Also celebrating on February 11
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.