Etching has nothing to do with the upgrading of these items.
Ebon, Furia, Etc armor all has certain Recipe's to upgrade them into their better parts... I don't see why this would be any different.
Considering they did show the upgraded Greatsword in the Update notes related to this update.
The only thing trading items to the NPC figures out is if you can Attach EVOLITH to the item, not if it has a SYNERGY recipe, they are 2 different things.
origional sword is from Fomors in the past: Chipped Scimitar.
Tried today and got this reply-
"Synergy Engineer: ...Alas. It's a shame, but it appears your chipped scimitar cannot be etched." There must be another process/quest in the mix, or this is not even going to be related to synergy.