Will a knife purchased from a sporting goods store work just as fine?
The bevel on the blade is one sided as stated by other members...this allows for better surface to surface contact when putting scion onto rootstock, making a flatter cut.
You can use whatever blade you want, but i"ve been told by wise men, that whatever knife you use, should only be used for grafting (otherwise disease and funky stuff can happen).
I use a grafting knife, but others hate them...just depends on u...