The Harbingers

This is less of a myth and legend but rather, an incredible series of events that led to the freeing of Thornden and its establishment as a co-operative member of Namarie.
The Harbingers were a rather small group of exceptional individuals who single handedly freed the ritual land gods and had a strong hand in ending the civil conflict between The Light (a cultish military group) and The Resistance of Thornden.
This much is seen as fact.
Their later achievements in killing an arisen archdevil and celestial god as well as their movements since are shrouded in a little more mystery though one thing is very clear.
They are all still alive and represent a fearsome defence of Thornden from other countries looking to take advantage of them.

Spread

The myth has spread across Namarie and almost turned the Harbingers into mythical celebrities, a large reason for this id the spread of the Varne Academies and Harbingers from there and also political spreading of this message to make the prospect of battle with Thornden a deeply unappealing one.

Variations & Mutation

It is still an early myth but is already being shifted and changed by word of mouth and exxageration. 
-The Harbinger of War was a re-incarnation of Helm and has been dead for years. 
-The Harbinger of the Tempest is a storm giants kin which explain her strength and attunement with the weather. 
-Luxanna Brightrose is Bahamut hidden in humanoid form. 
-Redacted has since taken over every thieves guild in Namarie

The truth and lies of the Harbingers have started to almost co-exist at this point.

Cultural Reception

It is seen as a story of heroism and a warning to those wishing to go after Thornden. 
It is also alot of the contribution to the popularity of the Varne Academies as many wish to train in the image of the Harbingers and become the next iteration of the group.

In Literature

There are storybooks, essays and historians looking into it. 
Many of these books were written by an academic based in the ruined tower of Primordius who goes under the pseudonym of Zakrios Xenolich. Though sources close to this writer claim they had a deeply personal relationship to at least one of the harbingers. 
Many tavern songs and plays were also written by one Montegue Hondra Adore. A former harbinger based in Thornden.