[Radek]

As far as my observations are concerned, then:

1. The higher weapon skill the higher average damage. But the damage seems to depend on your level, too.
2. The higher weapon skill the higher chance to hit at all. But this chance depends on your stats as well. With good stats, you will have a good chance to hit even without the skill.

In general, it's always a good idea to train your weapon skills for your favourite weapons as high as possible. But you can live well without all these skills at 12.