Was messing with Omniscience a bit last night, but what has you figuring Anrin Obi would be the choice sash? Most I managed was 567 on a Goobuue in Rolanberry, so while not the best test mobs, I couldn't really tell a difference between an Voidstorm/Obi and Penitent's for the +INT (if I remember right and the WS is INT based along with MATK). Harder stuff like Campaign mobs saw a drop in damage, usually like 216 for things that might've had Shell or native MDEF, but 316 on presumably INT-deficient job enemies (WAR, SAM, etc.).
If nobody's done level 1 testing, I suppose I could to kill time. Not that many really give a shit about a mage's WS potential.
