Boromir was impressed with the progress the pair had made. Though they were joking and laughing much of the time, Merry and Pippin proved to be serious about their lessons in swordplay. They would watch carefully as he showed the stances and moves, then follow his instruction nearly to perfection.
He'd been skeptical of their part in the Quest. He'd assumed they would be a burden, extra baggage to worry about and protect. But they'd been trying hard, with only a little grumbling about the food rationing. Boromir couldn't grudge them that. What soldier didn't complain about lack of food?