[Mirys considers drawing an illusion of the up-scaled rocket fist over Yang's existing arm to see what it might look like when it's actually made, but no, that would probably be a little too noticeable by any other people nearby, so she doesn't.]

It'd mean some extra weight, but that could make the necessary space if the parts inside don't need to be scaled up too. [It could possibly mean more punch, if it doesn't remain around the same amount of punch as is currently intended; the extra weight could offset any reduction in effectiveness that could come from there being some empty space inside.]

How much punch are you aiming for, anyway?