Main-hand/Off-hand Spell Selection

I've been curious but is there any benefits to using two different spells set on your main-hand/off-hand weapons?

For example Exsanguinate on main-hand and Incite Fear on off-hand.
I know you'd only get the buffs for the main-hand though.

Is there any sort of niche scenario where you'd use two different spells though? Or is it just a broken feature?