Dual wield when?

[Cynric]

Never. There is no such thing as "proper" dual wielding. If you look historically - back when they actually used swords, axes, etc. to fight - nobody ever[*] used two weapons at once. When possible weapon+shield or (rarely) a 2h-weapon was much preferred.


[*] There is actually one well-known exception. The use of rapier+dagger was not uncommon during the renaissance, but that is just about the only historically documented occurence of using two weapons at once.

Musashi?
Kodachi are primarily dual.
Short swords+ bucklers,
Axe+shortsword,double axe,
Scimitars, katars,etc.

I think you only know about English weapon history and barely that.