This is not archaic, but it is used infrequently. This combines both inversion and the subjunctive, and use of the latter has become more endangered for the younger speakers of English. Despite this, most speakers would use "if I were you" to describe the same sentiment. Inversion is apparently more endangered than the subjunctive.
I am the subject of the verb, but English treats me as an object. You can be used for both.
So OP's "reversal" principle doesn't really mean anything. If I say "I like you", I can't reverse it to *"You like I" any more than I can say *"Me like you" (unless I'm Tarzan talking to Jane).
In "If I were you", obviously "I" is the "subject" and "you" are (is?!) the "object". If you reverse the roles of the pronouns "I" becomes the object, so it has to be "If you were me"
Best Answer
This is not archaic, but it is used infrequently. This combines both inversion and the subjunctive, and use of the latter has become more endangered for the younger speakers of English. Despite this, most speakers would use "if I were you" to describe the same sentiment. Inversion is apparently more endangered than the subjunctive.
Were I you, I'd stick with "if I were you".