2 x Wurm Slayer...explain

[Eyry]

1.) I am just not educated on this sort of thing. But can someone explain to my why wurms can be Dual Wielded? When will this be nerfed? Will it be nerf?

2.) Can anyone provide a good link that has an in depth discussion about weapons in the Primary vs secondary. (IE: Do you have the slower weapon like a wurmslayer in primary or secondary)

3.) Is DW wurmslayer overrated? What if you are using an FBSS or other Haste item? Still overrated?

Thanks guys!