Flaw

Antonyms of flaw:
adornment, decoration, embellishment, enhancement, ornament.
Examples of usage:
  1. It certainly does not count for much that I should be unable to find any flaw in my own case, but I think it counts for a good deal that Mr. Gladstone appears to have been equally unable to do so.
    "Mr. Gladstone and Genesis Essay #5 from "Science and Hebrew Tradition"", Thomas Henry Huxley.
  2. Yes, a very carefully thought out plan of action, except for one flaw.
    "Dave Dawson at Casablanca", Robert Sydney Bowen.
  3. But before I come to that, I would dwell further upon this peculiar skill of Tolstoy's, this facility which explains, I think, the curious flaw in his beautiful novel.
    "The Craft of Fiction", Percy Lubbock.