Wustof knifes tend to be a heavier knife. They are great if you your a big guy chopping heavy stuff all day.
If you have the money I think your mom would be happier with a set from Global. They are quite light and very sharp.
If you want to spend less but still get good quality go for Victorinox Fibrox. Victorinox is on the lighter side of the heavier knifes, but they are a good entry level professional knife.