What do you want out of an AoS?

that would be really intersting but you have to care about balance. Just think of frost, slow and poison orb.
Would be imba slowed
Maybe you should still allow just one orb-efect weapon but create items which use multiple.
As an example a vampiric blade which steals life and lowers enemie's armor or something like that
Or a randomly chosen slow efect... i dont know but be aware of balance

I will observe your project interested

Balance shouldn't be an issue. Getting proc items won't be anymore powerful than castable or non-combat or pure damage items. In fact I think the majority of proc items will be more in the defensive end of things.