The image of the "veil" plays a crucial role in Moroni's elaboration of faith in Ether 12 because (1) the image of the veil ties together faith, weakness, and grace, and (2) their divergence in relation to the veil marks the difference betweent he power of the word and the power of the sword.  Where the sword professes strength and refuses to acknowledge the limit of the veil, the word takes as its strength nothing other than a confession of the weakness that the veil marks.

Thus, to exercise faith, Moroni argues in verse 19, is to be like the Brother of Jared "whose faith was so exceedingly strong" that he "could not be kept from within the veil."  As Moroni recounts, "When God put forth his finger he could not hide it from the sight of the Brothe rof Jared, because of his word which he had spoken unto him, which word he obtained by faith" (vs. 20).  In this parting of the veil, all of the concepts at work so far come together.  Note the logic of their intersection.  (1) The veil can only be penetrated by faith.  (2) Faith comes only in response to the power of the word.  (3) The word reveals to us our weakness.  (4) To come unto to God, to penetrate the veil, is to be shown our weakness and, more importantly, it is to be shown the truth of this weakness: that our weakness is in fact the strength of God's grace.  When, in the presence of God, we see the truth of weakness, then "weak things become strong" unto us, not because our weakness has been expunged but because we have ceded our debilitating claim to mastery or autonomy.

The irony of the veil, then, is that it is self imposed.  We are separated from God by our unwillingness to faithfully confess our weakness.  God is hidden by the veil that we throw over our own weakness in a vain attempt to cover it.

Adam S. Miller, Rube Goldberg Machines, pg. 105