Despite his sitting position and the way he presented the activity, Seth wasn't actually meditating. It was true that sitting like this was more comfortable and helped relax him, but that was it.
Even with a thousand hands at work, it didn't take too much concentration. Especially once he got himself into the rhythm of it all, it became as easy as breathing. At first he had to devote himself entirely to it, but now it only required roughly 50% of his concentration. Kind of like learning to play the piano.
At first he was clumsy and had to watch his hands or he would play the wrong note, but after a few months of practice his hands could glide across the keys and play a most wonderful rendition of 'Chopsticks'.
If he really wanted he could do this in the middle of a battlefield, although that would be a terrible idea for a multitude of reasons. Not that he was planning to. But he could if he wanted to.
