'Sharp' in the Bible

Then Zipporah took a sharp stone, and cut off the foreskin of her son, and cast it at his feet, and said, Surely a bloody husband art thou to me.

And if thou make me an altar of stone, thou shalt not build it of hewn stone; for if thou lift up thy sharp tool upon it, thou hast profaned it.

Then his master is to take him to the gods of the house, and at the door, or at its framework, he is to make a hole in his ear with a sharp-pointed instrument; and he will be his servant for ever.