Piandao does not quite touch Sokka's wrist. Just the gesture of reaching out to correct causes the young man to realize his mistake and change the way he holds his brush. There is still something awkward about his grip - he is sure Sokka never held a brush as a boy, and only rarely on his travels with the Avatar. The young man can write, of course, but he doesn't even have Jeong Jeong's casual sloppiness, much less Iroh's practiced elegance or his own patient calligraphy.
"Practice," Piandao murmurs. "It's like using a sword. You have to teach your arms to remember the movements."
Sokka nods, and there is some part of Piandao that wants to wrap an arm around him and tell the young man he doesn't need to practice, he is fine enough without this little thing.
Softness will do Sokka no favors, though, and the love for his student forbids Piandao from doing any such thing. Sokka will be a great man, and a great man must be able to write well.
"Practice," he says again and watches Sokka laboriously copy the treastise on the art of war.