Charm Virtue in 4e

I'm using some of the 4e book Land of Fire & Ice in my campaign and in it some characters have a +1 virtue called charm. This is distinct from the talent charm as some of them have that as well. What did this virtue do for them and how would you convert it to 5e?

I probably have access to the 4e book where the virtue is defined, but I didn't find it with a quick search.

Thanks in Advance

This page ( atlas-games.com/arm4/ ) has a searchable index for all of 4th Edition but it doesn't show a Charm virtue at all. Most curious.

Thanks for that resource. The way I see it there are two possibilities, either it's just an error in the Land of Ice and Fire book, or it's defined in a book not covered in that index. Either way unless someone has more information I'm likely to just ignore it at this point.

Could it be shorthand for Knack with Charm?