There are some schools that use a strict grid for merit…with GPA on the top row, and test scores running down the column. And for some if you have the same test score, but a higher GPA, you will get more merit.
That said, for most schools, test scores are the biggest driver for merit.
If you’re not happy with this school’s award, then quickly have him apply to schools where he’s get better awards.
Does his school weight GPAs? If not, then that should change as well.