Me on my WHM Chocobo. It took a LOT of grinding at the water sprites near Quarrymill, I already had all classes 50 so I had to do it the hard way as it only got to rank 4 by the time my Arcanist was level 50.

Anyway prepare for a long long grind! But you can spiritbond stuff at same time and make a lot of gil.

Rank 9-10 took about 12 hour of non stop pulling at water sprite camp.