The SL Maldraxxus / recently removed hunter talent Death Chakram would be a great start for a DH third spec since their glaives already fit the animation of the talent. Be interesting to actually see a very mobile mid to long range spec zipping around the battle field throwing their glaives with pinpoint accuracy.
Let them shoot poison darts from their wrist and expand on Grappling Hook. Right now DK is the only class that has grip mechanics designed for them in the raids, Morgan was talking about it in an interview.
Basically, let Outlaw Grappling Hook onto the ceiling like Spider-Man and while they are there they are counted as Stealthed. Let them grapple mobs to them, grapple players to them and give them an ability that lets them grapple to mobs and swing around them like Qhira from HotS while doing taser damage. The Grappling Hook can be a taser or something that has poisons, also possibly even explosives attached to it.
Rogue isn’t doing enough. It’s like the Rogue fantasy designer had a lobotomy or something.