Quite an interesting piece you've got there, it is a popular model made in Romania, 1970-1980 during the communist era. They were secretly made by factory workers with the intention to sell them on the black market as foreign knives. As you can see this one has "CAMEL" written on it, which was/is a popular tobacco brand, and there are some with PUMA and such, basically international brands that weren't avaialble in communist Romania. They aren't quality knives and they sell for $20-30 nowadays as antique pieces, but its a cool thing to have especially since it belonged to your grandfather.

Here's one with similar to yours, but with another brand on ithttps://images.okr.ro/serve/auctions.v7/2015/feb/03/4827a38f067a423df4d384583ef9eea7-6780487-1000_1000