ok, thats simple with something like a sword...
... I did some kenjutsu. It\'s not simple at all...

My main impression is, that strength does not only add \"damage\", but also greatly improves your chance to hit, as you can accelerate a weapon much better, which makes parrying a strong fighter a nightmare: You have to be fast, to parry at all, and even if you do, you may get thrown through the dojo, because of the impact on your parrying weapon.
And if your enemy is considerably stronger that you, not only the physis influences skill, but psychology as well: If you have reason to fear the enemys blow, you tend to be fear-stricken, which does not help, either... B-)
what about a bow?
i really don\'t know what can increase damage? i don\'t think strenght is that essential...
the more you trained \"ranged weapons\" the more info you should have on how to increase the damage given by that kind of weapons... 
The damage-model of PS makes it as you describe, but in reality it is somewhat different:
My experience with a real bow (which is backed up by literature): The stronger you are, the more damage you deal with a bow, BUT you have to use a bow fitting your strength, otherwise your damage and your chance to hit decrease, no matter if your strength is higher or lower than required by the bow.
Damage of an arrow, or of any given weapon, does not directly translate to \"damage\" to the body: The main function of damage is to penetrate armor (and in specialised literature, it is therefore mainly named \"penetration\", not \"damage\")
50% of the real \"damage\" is determined by the location you hit with your weapon - a joint is more supectible to get unusable than a muscle. The other 50% is the \"manstopping-power\", that is, the propability of a weapon or projectile to induce shock on your body (by pain, and by hydrostatic shock, which can kill you even if only a muscle is hit, if the projectile is fast enough).
Penetration and manstopping-power can sometimes be counter-productive, and sometimes they add up.
It\'s not an easy task to realistically determine the \"damage\" dealt by a weapon.
In my opinion, the damage-system must provide entertainment to the Players, realism is not necessary.
So, define what kind of combat would be fun for you, and then we could work out a fitting system... ;-)