Divus is a term used to refer to Roman deities or highly esteemed individuals (e.g. emperors). L&S give some classic Latin quotes, and you can also see books about Divus Augustus, Divus Titus, Divus Claudius, and etc.
Now, as many things in Christianity inherited from Roman customs and language, it seems divos was also used for saints. A partial analysis of this, related specifically to the word divos, seems to be in this pamphlet, published in 1865 in Italian, titled "Sulla deificazione nel senso pagano e nel senso cattolico ... relativi all'uso della voce latina "divus" nell'epigrafia cristiana". This can be translated as "On the deification of the pagan meaning and the catholic meaning ... relative to the use of the Latin term "divus" in christian epigraphy."
Now, I do not know Italian, but some few hints from a quick glance at it:
a famous epigraphist, Stefano Morcelli, wrote "expressly condemning in Christian epigraphy the use of the word divus".
"in this writing we have set out to do with greater clarity those same reasons, for which it seems to us however, the Latin word Divus for "Saint in paradise" is appropriate."
the author refers to an inscription in a certain Church of Saint Francis, stating DIVO FRANCISCO ASSISIATI SACRUM. There are also many churches with such epigraphs (e.g. here (bottom right) and here).
apparently, part of the argument against the use of divus was that Divi is too similar to Dei, and thus it might lead to the indication of the deification of saints to the level of God, a clear heresy.
Now, what can I gather from all this? There were indeed many books in Latin using divus to denote saints (e.g. here, here, and many more here). This might have been a "late" practice (I only found books or inscriptions dated from the second millennium), and might have died out after a debate (reflected in the text above) emerged. Still, more needs to be researched to reach a comprehensive answer.