To my understanding, its the following:
You cast Hurricane with switch 1 for say 1000 damage (even number for example)
You switch to weapon 2
It stays at 1000 since its a pre-cast spell.
The only difference would be if the - res were on switch 2. In which case it would then be applied with the 1000 from the switch 1 cast. It will not add the plus damage part to it though.
It's a bit confusing, but I hope that helps.