This is technically not a typo, but on page 972, he says, "Next, he Lashed himself upward with a subtle Lashing that left him weighing only a tenth his normal weight. He leapt onto the rock, and his lessened weight pushed the rock down slowly. He rode it down into the room below."
I understand what he was trying to accomplish but gravity is a constant and, as such, Szeth should've fallen at the same velocity despite reducing his weight.