Let's side-by-side them, so there aren't any Serf's Parma issues:
Linguist: Minor General Virtue
You are extremely proficient learning new languages. All Study Totals for any Language are increased by a quarter, as (are) any experience points you put into any language at character creation. Both Living and Dead languages are augmented with this Virtue.
Polyglot: Minor, General Virtue
This virtue grants Affinity for all Living Languages. The character is adept at learning the spoken word, but cannot gain experience points from texts on a language and has a -3 penalty to Living Language ability scores (other than his native language) when attempting to comprehend something he reads. He benefits normally from exposure, a teacher, or practice. The character still needs Artes Liberales to read and write.
(e.g. A Catalan character from Barcelona with Polyglot has a Living Language: Greek score of 4. When reading a Greek Bible, his score of 4 is considered a 1.)
Polyglot, the Altimate Rewrite: Minor, General Virtue
This virtue grants Puissant for all Living Languages. The character is adept at learning the spoken word, but cannot gain experience points from texts on a language and has a -3 penalty to Living Language ability scores (other than his native language) when attempting to comprehend something he reads. He benefits normally from exposure, a teacher, or practice. The character still needs Artes Liberales to read and write.
Example: A Catalan character from Barcelona has Polygot, and spends a season in a city where Living Language: Greek is spoken. After a couple of months - ie, after 5 out of the 8 language xp are earned for the season - she is "haltingly functional" in Greek, although she can only barely pick out a few words if she attempts to read a book or a sign. A regular character would, at this point, be able to both speak and read Greek at the "basic questions and answers" level.
After a full year in the the Greek city, our Catalan lass is fluent in spoken Greek, albeit with an accent everyone assures her is charming. She still has a lot of trouble trying to read Greek, though. A regular character would, by this point, be "haltingly functional" in Greek, both spoken and verbal.
I prefer my suggested version because it allows a well-traveled character to act as a basic interpreter for just about anywhere he or she has spent any time in. "Yeah, I've been around. I can make myself understood in English, French, German, Italian, Spanish, Greek, Arabic, Hebrew, Norse . . ."
-Albert