Hi AdW. If by “leaded glass” you mean an item which has been formed by joining separate pieces of glass between lead strips (known as “cames”), I have never seen such a thing. Note that it would not be suitable for drinking.

However, I suspect you ran into the term when the person was referring to the practice of adding lead to molten glass as an item was being formed. This imparted certain characteristics to the glass, among others making it more easily cut (which is another term which doesn’t mean what it seems to mean).