It seems that resistance to normal weapons + enchanted weapons cancels out the resistance. At least in the wiki it says 100 resist normal weapons is useless against creatures and enemies equipped with dremora weapons such as in oblivion plane.

But does that mean weakness is also cancelled out? That would make weakness less of a hinderance on you as the most dangerous enemies use enchanted weapons.. I play with a mod that makes some star signs have weakness to weapons.

Intriguing question.....

I would have to assume that silver/daedric/enchanted weapons would not do additional damage to a character with a weakness to normal weapons.

The game treats weaknesses and resistances the same way. In all the appropriate equations, there's only a single value, which can be either negative or positive, meaning either a weakness or resistance. So, in effect, a weakness is just a negative resistance.

Silver, daedric and enchanted weapons "ignore weapon resistance." That means that, in equations in which it would apply, any value for weapon resistance is simply ignored. That would seem to apply to a negative value just as it would a positive one, so it would not only ignore a resistance to normal weapons, but would ignore a weakness (negative resistance) to them as well.

I don't know what it would really do, but that all makes sense to me.

Weakness to Normal Weapons is bugged and has no effect, except maybe to cancel out Resist Normal Weapons.

Did you test it with non-enchanted and non-silver weapons?

I didn't do the testing myself, I've read a discussion in another thread in the forum. I don't remember who it was that did the testing, they gave themselves a weakness and then went to fight bandits. Most bandits have non-magic non-silver weapons.