You know, because of this debate, I went back and looked over the abilities with an eye specifically for an offensive CNJ build. I think it has a lot of potential. Grab the cross class spells and abilities from THM and a fill your remaining two slots with ARC emnity- abilities. Between CNJ's ability to increase it's own offensive magic power, and reduce/regain MP over time, it could be a real powerhouse offensively. You sacrifice WHM, but that's only to be expected; you can't have the best of both worlds.