Quote Originally Posted by qwertyX View Post
Do the Eidolon/Weapon upgrade quests change elements, or are they just there for the first week?
Are you referring to the SP quests that drop eido/weapon enhance mats? They got reworked recently and should be available everyday at all times. The eido one is always random elements and the weapon one doesn't have elements.

Btw, once you start doing events properly though, you usually won't have a shortage of enhance mats.