I would greatly appreciate if anyone can remember the books in a trilogy (?) which contained these elements.

A human colony on a remote planet. Some small number of colonists encounter talismans which cause them to transform into alien's from an extinct race native to the planet. As part of the transformation, the changelings acquire the memories of native people from past age when the alien race was dominant on the planet. The original human personality merges with the native personality. In addition, the changelings have a strong aversion communicating with the remaining humans - such that upon encountering a talisman, a colonist the simply disappears into the woods. Hundreds (or thousands) of years earlier, the natives were wiped out in a war with an ancient enemy (evil) - possibly a namer beginning with W. The enemy is still on the planet but the human's are unaware of it. The ancient enemy is awakening and the band of changelings fights it.

The changeling band use iron age tools and weapons with some fantastic elements as well. The main protagonist was a guard or swordsman.

I believe the native ages (eras) were named after colors such as 'in the time of the red leaf'.

In the final book, upon defeating the minions of the ancient enemy (many mechanical in nature such as animated space suits), they destroy the enemy which turns out to have been a deranged ship's computer.

I think it was written between 1960 and 1985.

Any ideas ?

Found it:

Judgment on Janus and Victory on Janus by Andre Norton.

Now to reread it