Yeah, I actually agree with TGVA's assessment; a Seele has no power of its own to draw in reiryoku and create a blade. That power comes solely from the Quincy using it, and as far as I can tell only Quincy can do it so effectively. Arrancar can use Gonzui to draw in souls, but they can't pull in just spirit particles, nor can they use the souls for anything but sustenance. However, that's what we've seen in canon.

Perhaps the Arrancar could use an alternative source of power? Perhaps using their own life force to power the blades? However, that price would likely be not worth the power given, so it would be quickly scrapped. However, we'll see what happens. I'm interested to see what Nick and KD come up with!