When Ophelia, even in her insanity, says "You must wear your rue with a difference," she is a true daughter of the Polonius family—always observing differences and making fine distinctions.
Hudson, in adopting the reading and, explains his understanding of it by a paraphrase —"I hold my duty both to my God and to my king as I do my soul." After reading this explanation one would be justified in inquiring, Holds his soul to whom? It is difficult to make consistent sense out of and; and the more one contemplates it as the substance of a Shakespearean remark the more hopeless it appears. The First Folio, besides offering the proper sense, is even correctly punctuated to enforce it.
In 1st Henry VI, iii, 4, 12, we have: First to my God and next unto your Grace—an interesting parallel.