Flavor
Yes i've heard it said before that the druid restriction is just flavor.
Look at the FRCS. In forgotten realms, druids that worship meilikki (sp?) can use any ranger weapon (martial weapons).
In defending the right for them to be able to do that, it had to be stated that the restriction was just placed there for flavor.
But the restriction makes absolutely no sense. No other class in the game has a restriction on the weapons they can use.
A wizard can run around with a great axe, as long as he pays some form of cost to gain that ability (feat, multi, -4 to hit, etc).
The druid *can* use a scimitar, but can't use a bow? That's just wierd. A bow, made out of wood, cannot be used by a druid, however a masterwork metal scimitar can...
All i have been able to figure out, is that it must be the bow string. Now what do they put in those strings...?
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In my campaign the druid's restriction on weapons has been removed. They don't gain any weapon's, but if they acquire proficiency in them somehow, then they can use them.