I'm not sure I'd read to much into the hand ground thing, I'm fairly sure that mass produced knives like the Rapalla's were stamped then finish ground like most knives are. If a guy grinds a edge on a stamped blank, does that make it a hand ground knife? I guess it depends on your definition of hand ground.
I'd say that its mostly a advertising booster, a common type of thing in the knife, and most other, industries. Most people don't know the difference between a hand ground blade and a machine ground blade.
That being said, I love the Rapalla line of fillet knives. They are the industry standard and fine performers. I have a very old 4 inch blade model that is down to about 60% of the original blade, but sharpens up nice and keeps on cutting. When it finally gives up the ghost, I'll just buy another one for 10$ and use it the rest of my life. Like scandi made Mora's, they are a great value in the knife world. If I were you I'd just go ahead and use and enjoy grampa's knives for what they are, a link to your family traditions. Take care of them and you'll probably be able to pass them on to your kids.
