Hullo, lilalila,
Welcome to the
Desolation forums! It's always good to see a new face around here, and the folks are very friendly in these foroums and will offer advice and answer questions willingly. Glad to have you here!
As you may have noticed, there are no actual rules per se on worn weapons. Page 196 of the rulebook, in the second column, gives good guidelines. Worn weapons are chipped, unbalanced, dull, weak, or otherwise not as good as they could be, and rolling a Botch while attacking with a weapon in good condition causes it to become worn. Another Botch, and the worn weapon becomes broken. However, broken weapons can still be deadly, such as a sword that is broken serving as a dagger.
In terms of their combat abilities and the like, the GM is ultimately responsible for determining this stuff. A chipped or dull weapon could be ruled to have a -1 or -2 penalty to damage. An unbalanced weapon could have a -1 or -2 attack penalty. Weapons can, of course, be fixed either through repairing them or sharpening their edges once more, but it really depends on how the GM decides to handle stuff. Other game effects are at the whim of the GM, but this is really something that I've always felt should be addressed in the game, or perhaps some additional PDF or some such.
Overall however, I would have to say to you that common sense should guide your path in this regard.
Hope this helps.