I've read that you have to use the mognet to start a mission with Sara - a piece of her jewelry is broken and she needs you to find someone to fix it. you find the smith in a fixed location (forgotten where) and she'll agree to fix it as long as you try to keep an eye out for a rare metal on your journey - Oriclcum? Anyway, when you DO find that elusive metal after a ?boss? I think, she'll appear in a random location when you cant find her where you first met her. give her the metal and she'll tell you that she'll give you something if you talk to her when the job you're using is at max.

so yes, you need the mognet.

And its damn annoying - Ninja, Monk Geomancer and Devout are at max, and i can't get nada!