Personally I think Garuda's Van is the best 2-handed, it gives INT+30, Magic Accuracy+25 and Enmity-30. All very good.

Aubreists's Whisper is nice if you suffer from big number syndrome as it will boost your critical hits on mobs, but at the cost of accuracy (and no bonus at all when doing non-critical attacks) I do not see it as a very useful weapon. If you can consistently time it with Flare tho it could have its use ^^

Maleficent Mogstaff is very nice for its Magic Accuracy of +30. However Garuda's Van is much better (5 less accuracy but a lot more to make up for that). However, the Mogstaff is cute ^.^, and easier to obtain.

The Ivory Staff (Magic Accuracy +10, Magic Critical HIt Rating +10) has some promise, but only if you start melding. You can add Lightning Magic Potency +30 (but each one costs upwards of 2-3M), or just add INT +20. However, would still not be as good as Garuda's Van. You would have to 2x or 3x meld to start comparing with Primal Weapons at this point (and that will be *VERY* expensive. 2x Lighting IV on Ivory Staff, prepare to spend about 20-30M, *IF* you can find/get the materia.

My honest realistic recommendations:
Get Garuda's Van if you can. Otherwise Maleficent Mogstaff. Unfortunately, some of the best BLM weapons right now are still one-handed (which is what you are trying to avoid).

Perhaps Skirmish or the Next Primal will have a two-handed BLM weapon ^.^