[Indemaijinj]

You are partially right Pirengle.

They don't really stack. Rather they are superimposed.

Say, you have four dots in hammers as a fighter, then dual to cleric and put one dot in hammers. When your fighter levels reappear, you will have four dots in hammers NOT five.

Thus the best way to build a multiclass is to forget about your old weapon skills and learn something new when you dual. Let's for example take a berserker -> Cleric. He starts his life with all his points put into hammers and dual-wielding. He will keep on developing those skills exclusively until he reaches level 9. Then when he duals he will forget about his hammer, start wearing a shield and put his points into maces, flails, staves and slings.

When his fighter class reappears it is time to take some of those new weapon skills into grand-mastery.