Two versions contributed by Alexander Shurbanov
He comments on the meanings of "светъл", transliterated "svetal", back-translated with "fair":
The basic meaning of the word used in both translations (svetal) is "bright", "light-coloured", of "light complexion"; but it can also metaphorically suggest "spiritual purity" - thus the word comes very close to the English "fair", though the two cannot be said to coincide completely: the meaning of "just", for instance, is not there at all in the Bulgarian word, though, as I have suggested, that of "virtuous", 'pure of soul" can be present.
Valeri Petrov (Sofia, 1973):
Щом „светла доблест” казва се навред,
съвсем е светъл черният ви зет!
(Shtom “svetla doblest” kazva se navred,
savsem e svetal cherniyat vi zet!)
If “fair valour” is the universal phrase,
your black son-in-law is absolutely fair!
Alexander Shurbanov (still unpublished):
но зет ви с чистата си добродетел
не е тъй черен, колкото е светъл.
(no zet vi s chistata si dobrodetel
ne e tay cheren, kolkoto e svetal.)
but your son-in-law with his pure virtueis not as black as he is fair.*