Hey, bringing to light a couple relevant patch notes:

[3.0] Gear from the following trials and duties can now be sold, desynthesized, or submitted for expert delivery missions:
Esoterics Gear (Item Level 200) / Esoterics Gear (Item Level 210) / Alexander: Gordias / Alexander: Gordias (Savage) / The Limitless Blue (Extreme) / Thok ast Thok (Extreme) / The Minstrel's Ballad: Thordan's Reign

[2.0] The following items can now be desynthesized:
Iron clapper / Item Level 210 gear obtained from the Diadem.

[2.0] Maximum desynthesis skill has been raised.
Maximum desynthesis skill has increased from 180 to 220.
Overall maximum desynthesis skill has increased from 560 to 680.
I accidentily messed up my desynthesis skill levels, so I'll be able to test at 179 and 180 if I can't fix it by patch day. I have an almost-full inventory tab of these items to desynthesize, mostly Alexander: Gordias gear.