From what I understand, all the spheres will work in a sort of 'combat' manner like this.
Adventuring, you will be fighting the mob with combat tecniques.
Harvesting, you will be fighting the tree, or rock, or whatever.
Diplomacy is fighting the conversation.
Crafting is fighting the crafting table.
I should put fighting in quotes, I guess.
I think this is how it works, anyway. Everything I recall reading has pointed in this direction. It sounds exciting to me! I want to parlay, to fight with words instead of swords. but then, I've always been a quester and healer, I have to stop to talk to every new NPC I come across. It seems Vanguard will finally be the game where this interest of mine will be rewarded a lot.