I think the next step for tongs is the study and understanding of Divine Magic. Because they can do it. Meddling with Dhar doesn't end well, but at the same time, Dhar is not just the substance of Chaos and evil magic, it's also the stuff Gods and the Aether are made from. Souls too, probably, unless one thinks each souls is single wind aligned. I'll bet you that's the trick, as it is with regular magic. Souls and gods are the stable, non-corupptive version of Dhar.
If you want to channel godly magic, you have to align your soul to your God. So if you want to channel multi-wind magic, you can only do one that matches your own soul. It's how the gods do it, as noted by Kragg: That the power of a God, before use, is no different then the God itself.