@Warsaw Will, Feb 8th 2014. Yes, very well put.

Hey! I think I’ve cracked it. Both structures (one of the + superlative and one of the + comparative) are correct but have slightly different meanings. The above post by Goofy (May 15th 2009) shows that one of the + superlative has been used for a very long time indeed. The one of the + comparative form is, I would say, much more recent. If you Google it you’ll find dozens of examples from various sources, some reliable (The New Yorker …), others less so. Here are a few:
• One of the more widely accepted definitions of a native speaker is someone who was born in a particular country and was raised to speak the language of that …
• One of the more interesting aspects of having a proper, honest-to-god 9-5 job (with these awesome guys) is that I find myself being way more selective with what …
• It's considered one of the more advanced titanosaurs ever found. One of the things that made it unique, aside from its tremendous size, was it's ...
• He said: “I have seen a number of cases of abuses of people's rights in the family courts, but this has to be one of the more extreme. “It involves ...
• Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum ...
• One of the more heart-warming stories to zoom around the Internet lately involves a young man, his dying grandmother, and a bowl of clam ...
• The Grand Challenge proved to be one of the more humbling events in automotive history. Its sole consolation lay in shared misery. None of ...
I think you’ll agree that the use of the comparative diminishes the exceptional nature of the event under discussion. So, “one of the more obscure Latin words …” implies that the word isn’t incredibly obscure, but fairly obscure. Similarly, “One of the more heart-warming stories to zoom around the Internet lately …” implies that the story isn’t necessarily among the most heart-warming but is pretty heart-warming nonetheless. Voilà!

In reply to Nemo's comments (June 2013), you might perhaps consider applying for a sub-editor position at the Economist. Here's the opening sentence of an article published in 2012:
“One of the more surprising growth industries to have taken off during the current period of economic downturn and austerity has been the happiness industry”
and here's the link:
http://www.economist.com/blogs/feastandfamine/2012/04/happiness
Your comment “One of the (comparative) is always wrong. It's always one of the (superlative)." is probably one of the more erroneous I’ve come across.