Bret Devereaux, at "A Collection of Unmitigated Pedantry", recently had a very good series on Rings of Power, that touches on issues that go well beyond that series, with problems in how one's handling of medieval settings in fantasy fiction can go wrong:
The Siege of Eregion, Part I: What Logistics?
The Siege of Eregion, Part II: What Siege Camp?
The Siege of Eregion, Part III: What Catapults?
The Siege of Eregion, Part IV: What Siege Equipment?
The Siege of Eregion, Part V: What Tactics?
He's also had two other post that are not strictly part of the same series, but do have some broader thematic links:
Why Celebrimbor Fell but Boromir Conquered: The Moral Universe of Tolkien
How Gandal Proved Mightiest: Spiritual Power in Tolkien
The latter is especially good, and is the one to read if you only read one. One thing I will add is that the Wizards' staffs seem to function as insignia of (spiritual) authority, and thus (like their words) as part of how they exercise authority (which for them can have effects on the world) -- this seems quite clearly indicated by Gandalf's breaking of Saruman's staff, in which, having been promoted by higher powers, he is effectively removing Saruman from office, both substantively and symbolically. (It's an interesting comparison and contrast with the Ring. The staffs seem to be just effective symbols of an authority received by mission from a higher power; this is essential to the function of Wizards, who are in fact massively more powerful than they appear but who are only authorized to use that power for purposes related to their mission. With the Ring, however, Sauron has alienated much of his own power into an artifact in order to use his own power more effectively -- he is a case study in the evil of using yourself as a mere means. The Ring is not a sign of his authority, because he has no mission, but just is partly Sauron himself. And the closest we get in The Lord of the Rings to seeing Sauron himself directly exercise power is when Frodo, seeming to be a figure in white with a wheel of fire on his chest, faces Gollum and out of the fire a commanding voice tells Gollum to go, and if he ever lays hands on him again, he shall be cast into the Fire of Doom. And it is so. Frodo is not Sauron -- but the command through the Ring has much of the authority of Sauron, limited only by the limitations of Frodo himself. Someone like Gandalf or Galadriel could do far more with it, effectively adding much of the power of Sauron to their own; and Sauron, of course, far more still.)
