LW S3 ascended accessories vendors.
The other vendor is in Ember Bay.
Bloodstone Fen: in the camp at ground level NW corner.
Ember Bay: near the asura gate at the first waypoint.
Lake Doric: right by the DR portal and first waypoint.
Draconis Mons: right on the beach by the sub and the first waypoint.
Siren’s Landing: right by the first waypoint.
Look for the Unbound Magic icon – little rainbow colored swath.
Edit: right, just the accessory, not the other trinkets. That’s Ember Bay, as Kisanth wrote.
I could only find 2 accessories. Bitterfrost zone for unbound magic and winter berries and Ember Bay zone for unbound magic and petrified wood.
Thanks. The vendor in EB was the one I was missing.