I've seen a few people discussing this topic, on various blogs and forums: the idea of weapon damage in D&D being determined not by the weapon itself, but by the class of the character wielding it. The most commonly propsed system is that characters do damage based on their hit die (d4 for magic users, d6 for thieves, d8 for clerics and d10 for fighters - using the AD&D class hit dice).
It's an idea that I find very appealing. 1. It's simple, super simple. 2. It (potentially) does away with that old D&D stickler - "why can't my wizard / cleric use a sword?".
So with damage by class a wizard can use a sword - he just won't do much damage with it. This makes sense to me. Of course, anyone can pick up and use (almost) any weapon, but without proper training (like, say, being a fighter) they're not going to be able to use it at full effectiveness.
At the low end of the damage spectrum it seems to make sense. However I've wondered if it makes sense at the other end (fighters). Is a trained warrior really as effective in combat with a dagger as with a longsword? I don't claim any knowledge of such things, but I presume not, otherwise the longsword would probably never have been invented.
So, what I've been thinking is that a mixture of the two systems would probably work - damage by class and by weapon. This sounds like it's going to be complicated and involve tables, but it doesn't! All you need to do is say that any character can use any weapon, and all weapons do the damage listed as normal - BUT up to a maximum of the character's hit die. So a wizard wielding a dagger, a club, a sword - any weapon at all - will do d4 damage. But a fighter wielding a dagger will be a far less formidable opponent than a fighter wielding a 2-handed sword.
(By the way, I'm sure this idea is subconsciously inspired by Savage Worlds, where damage is by weapon but limited by a character's Strength.)
The only trouble I can see with this (or other damage by class systems) is that it takes away one of the fighter's big advantages - having no weapon restrictions. Of course the fighter has also just gained a new big advantage - being the only class capable of dealing maximum damage with big weapons. I'm not sure if this balances out though.
I'd say probably clerics would be the big winners here, going from being able to use a very limited selection of weapons, almost all of which do d6 damage, to being able to use any weapon, many of which deal up to d8 damage. In that respect I'd consider reducing clerics' maximum damage to d6, that seems more balanced.
I'm interested to hear anyone's thoughts on this matter!