Not exactly sure why everyone wants that dagger..personally the cane is the better loot. Underwaterness! (not many things give unlimited underwater ability, diving helmet =eng).
Whereas the dagger has a fairly good chance of proccing, so gouge wnt work that well for you. My rogue is sub specced so he loves backstab, a DoTing weapon would suck as timing a gouge, leap and BS between ticks would be irritating.