One of the most fantastical elements in Tolkien's mythology are the glowing elven swords. Sometime during the First Age, fueled by wars with Morgoth and the orcs, elven craftsmanship reached its zenith. A featured mark of elven blades made during this time was their unique ability to glow blue when orcs or goblins were nearby. The swords retained their power over the years and three very important blades (Glamdring, Orcrist and Sting) appear in The Hobbit and The Lord of the Rings. In fact, this "magical" power is featured quite heavily in the books as seen in this example from chapter four of The Hobbit, "Over Hill and Under Hill".
He [Gandalf] took out his sword again, and again it flashed in the dark by itself. It burned with a rage that made it gleam if goblins were about; now it was bright as blue flame for delight in the killing of the great lord of the cave...
...They [the goblins] came scurrying round the corner in full cry, and found Goblin-cleaver [Orcrist], and Foe-hammer [Glamdring] shining cold and bright in their astonished eyes.Later in chapter five we learn a bit more about Bilbo's sword, Sting.
It [Sting] shone pale and dim before his eyes. "So it is an elvish blade, too," he thought; "and goblins are not very near, and yet not far enough."
In An Unexpected Journey Peter Jackson and Weta had no issue making Sting glow blue, but for some odd reason neither Glamdring nor Orcrist act the same way. Yet, during the film a Goblin even goes so far to (accidentally) pick up Orcist. The sword obviously has a terrifying effect on the goblin as the brute hurriedly throws it on the ground, but as he does so not the faintest glimmer of blue can be seen:
Later, as Gandalf slashes the belly of the Goblin King we could at least expect a small flame of blue? Right?
The same problem exists in "The Lord of the Rings" films. In chapter five of Book II, The Bridge of Khazad-dum, we read that as the orcs approached, "Glamdring shone with a pale light, and Sting glinted at the edges." In that sequence in the film we see Sting glowing blue, but not Glamdring.
Now the only question is why? Why would Glamdring and Orcrist (swords that belonged to Turgon, High King of the Noldor and King of Gondolin) not glow blue while Sting (a short sword that had no recorded history prior to the Third Age) does? It doesn't make sense and I can't explain PJ & Co.'s reasoning behind this deliberate deviation from the books. Surely an extra glowing blade isn't too much for the wizards at Weta. They went to great lengths in every film to make it look the best it could be so technical issues seem an unlikely explanation. Are they trying the single out Bilbo and Frodo's swords? Make them and their weapon seem more important? That doesn't make much sense either since in AUJ Gandalf explicitly tells Bilbo that his sword will glow blue because it's of "elvish make". See for yourself in the clip below.
Yet, Gandalf's elvish sword (which is also identified as such in at least two other scenes in AUJ) doesn't glow blue in the films? Why? I'm afraid I don't have a good answer. Perhaps there's some forgotten interview out there where PJ discusses it or perhaps someone makes a comment about it on the exhaustive hours of commentaries. But, whenever a reporter gets a chance to sit down and have a geeky conversation with Peter Jackson, the writers, or the design team about the Middle-earth films he/she needs to bring up the non-glowing swords.