The important part is that the magnitude is one. You're making a big deal out of nothing, you know what it is now.
Anyway I feel guilty for partly filling this thread up with bullstuff, so here's the math you need
function getDifVec(%orig,%pos,%vec)
{
return vectorScale((vectorSub(%pos,%orig)),%mag);
}
%orig is the would be the position of the golf club head, %pos is where it hits the object, %mag is how hard you want the hit to be