I really don’t want to target ethics per se, but what I see as the underlying point. I think W is saying (in other words) that any sign either has a factual referent, or becomes (a) metaphorical* or (b) nonsense.
Example: the sign “goat”. The sign consists of a signifier and a signified. The signifier is the letters g-o-a-t (or their phonetic equivalent). The signified is what the signifier means—what it signifies and describes—e.g., “a mammal with certain physical characteristics, etc., etc.”
The referent for the sign “goat” is—that critter over there (to which I now point).
Example: the sign “unicorn”. The signified is a particular mythological animal with certain “physical” characteristics. However, there is no real-world, factual, referent. (One might say that the referent is, say, this mental image, or that picture in a book; but I think W would say that such things are simply alternative—e.g., pictorial rather than verbal—signifieds.)
Absent an actual referent, any talk about the unicorn becomes (a) metaphorical—e.g., “a unicorn is like [simile] a horse, but with a horn like...” with respect to some factual referent(s); or (b) nonsensical—“a unicorn is a nonexistent existent”, or “a unicorn is a dardyvart”.
It does not matter how far one extends the chain of terms, nor what modifiers one applies to any of the terms, eventually one either ends up with a referent or one does not.
Now, the question you have raised is (in my words): “Can there be a (factual) referent that is both (1) inexpressible by language—except metaphorically (by simile, or allegory)—and (2) not subject to ostensive definition (e.g., by observation, by pointing)?”
This is where I think we get into W’s claim about “absolutes”.
Consider the sign: “whole” (as a noun). Now, I might say, by way of attempting a signified, that by “the whole” I mean: “everything that is the case” (Wittgenstein), or “the all-of-all-of-all-of-it”, or “the totality that has no edge” (scottishinnz). But— if I do not understand “the whole”, do any of these alternative statements really add anything? Do not they, in turn, need explanation?
How does one describe “the whole”, considered as an absolute—i.e., as the all without any other? Does “the whole” have any proper analogy? If so, where from? Does not any attempt at analogy draw us back into the domain of the relative (as W puts it)? Does not any analogy—or simile or allegory, etc.—come from the domain of the relative?
In the area of religious philosophy, the great divide seems to be between non-dualism (which speaks in terms of the Whole) and dualism (which speaks in terms of the (i) world** and (ii) another—e.g., God). Now, I do not think that non-dualistic language is any less subject to the considerations raised by W, than is dualistic language. I do think that dualism raises a whole host of additional issues that are similarly problematic: What is the nature of this “other”? What is the relationship between the “other” and the world? What is it about that relationship that requires their ultimate (“absolute” ) separability? Etc., etc.
Consider the sign: “God”—
Bbarr has mentioned another use of language that is neither propositional nor descriptive. The term he used was elicitive. Elicitive language includes metaphorical speech, as well as paradox and plain nonsense—aimed at eliciting in the listener an experience of that aspect of our existential condition that is non-conceptual and ineffable. Whatever we say (after) about that is subject to the limitations laid out by Wittgenstein.
In the following post, I simply list some statements by W from the article that pertain to religion. And in the post after that, a brief commentary of ethics.
* He uses the terms “simile” and “allegory”, but both are kinds of metaphorical speech.
** W’s “everything that is the case” (from the Tractatus).