The only saint I can dig up is FEBRONIA of Nisibis (now Turkey) who is said to have died as a martyr in the early 4th century.
If you google FEBRONIUS, you will get to Johann Nikolaus
von Hontheim (18th century), who used F. as a pseudonym (I didn't go all the way through some 9000 hits).
My Greek dictionary (not a very good one) has no entry that would resemble either name.
My Latin dictionary (Menge/Güthling, not so bad) offers:
februus, cleansing (originally with smoke; this is where the name of the month of February originates)
This is all, I can come up with.