>You can sharpen them, unlearn sharpen, relearn sharpen and sharpen them again? I didn't know that<
No, that only helps if you learn sharpen to a higher level the second time, and then you can increase the sharpening.
Sharpen isn't exactly a useful skill to always have points in - so the point (pun intended) is that it is good technique to learn the skill, use it, unlearn it and put the points where they help you e.g. magic, traps or weapons.
