Whoever gives away the khopesh gets the curse (except for Louie, the first time). If they keep it, nothing will happen. This gives them something of an incentive not to give it away.

They do know they will not suffer serious harm from the curse, though they will legitimately lose blood. It will be the equivalent of a rather nasty cut, that bleeds a lot but not so much as to cause any danger from exsanguination.

Louie will never be cursed.