Warfare gives 5% more damage on every physical attack, Dual Wield gives 5% more damage on attacks using two one handed weapons. So let's say, you're using Necromancy too, Mosquito Swarm will benefit from Warfare (despite scalling on Intelligence, its physical damage) whereas Dual Wield wouldn't affect it all. It is, of course, if I understood it correctly.

Plus, I haven't really tested it, but I like to believe that not speccing into Dual Wield, leaves the possibility to use a Spear for harder hits on Warfare skills as a Finesse Rogue character (No idea at all if that's going be ever useful, but why not).

And btw, with the changes to Haste, I believe it is not as mandatory as it was, isnt it ?

Anyone knows if the smoke cloud of Aerothurge/Scoundrel if worth anything ?