"sharp" can not only wind up cutting you at some point , accidents do happen , but a sharp edge wears faster ( digging through dirt , rocks , etc ) and can prematurely wear out your digging tool. Usually just keeping a crisp beveled edge is a good idea , its not any more dangerous than it has to be , it will last longer before needing a touchup , and you arent grinding away your digger as quickly. All the while its still just whats needed to punch into the ground well.