Nope. Weapons that are already split damage cannot be buffed.
Moonveil isn't remotely as OP as people made it out to be (especially compared to some of the newer game-breaking videos posted). You want lots of int, but there's a point where adding more dex gives more AR than adding more int. I haven't tested thoroughly to see if dex increases the damage of Transient Moonlight though. I suspect that it does because Sword of Night and Flame build videos say that it scales the beam and wave off of the weapon's total AR. So to answer your earlier question, int at least 60 for the best staff, probably more like 70-80 since sorc scaling on a new staff doesn't really kick in until you're quite a bit above the minimum req to equip. 40 dex for a good chunk of extra AR and a bit of cast speed. At least 26 mind to summon Tiche. 40 vigor, and then however much end you need for what you wear.
That's probably more than 150, but Radagon's Soreseal permanently occupies one of my talisman slots. Even the str on it is useful since brass shield takes 16 to equip.