How is it you don't add this up to a double vuln, if your target is indeed vulnerable to both?
What it's saying here, is that if someone is gaining more damage from the weapon type but resisting the damage type, it's a wash as to whether they count as vulnerable or not in the end. The examples being a fire resistant elf hit with an iron flaming axe. Although the weapon type means the elf takes more damage, the flame resistance lowers it again. Are you getting this yet?
If you're STILL having problems understanding that, it means unless there is a piece of code that specifically limits double vulnerabilites or the amount of extra damage a strike can do - that you can gain extra damage twice from each seperate form of vulnerability. While the long held myth that wrathing maces also count as blunt is complete bollox (no weapon has two damage types) the weapon type is completely revelant in ALL strikes. This is further backed by the fact that a druid might not resist wrathing attacks - but if they come from a metal weapon, it'll reduce the damage anyway. If the mechanics aren't made transparent by all this theorising, I'm not sure what I can say to communicate how it DOES work.
Since you've already started pulling out the insulting tone however, I'm going to assume you're going to dance around this obtusely to avoid saying 'whoops, you're right'. So I'll level this at you - how about you shut up, and go ask the imms. AKA the people who know for sure. If they go ahead and say double vulns don't ever occur, I'll go ahead and ban myself for a month. *tips his hat*
Yhorian