Hi Nya,

Info on my Desynths so far:

As a Weaver Desynth Level 103, I tried:

* Rainbow Robe of Casting HQ (iLevel 115) - with Quad Materia Meld I had a 40.xx% Chance of Success.
* Skill Up: +0.76!
* Battlecraft Demimateria II x 2
* Lightning Crystal
* Wind Crystal

* Holy Rainbow Cap of Casting HQ (iLevel 115) - with Quad Meld Materia I had a 41% Chance of Success (I got to 104 Skill on previous item).
* Skill Up: +0.54
* Rainbow Thread x 1
* Lightning Crystal
* Wind Crystal

Hope this helps.