Why do cheese knives have holes or spaces built in to some cheese knives? It's rudimentary. Less surface for the soft cheeses to glean onto.
The most widely used cheese knife is the regular knife with two prongs at the tip. These are meant for firm cheeses and the forkish end is to serve others or yourself. There is a putty knife looking flat cheese knife and a cleaver style, they are for cutting chunky or crumbly cheeses, or to shave pieces of cheese.