Can someone help me design a melee dual-wield vampiric build?

Okay, I’m pretty new to the game, but I’ve been doing massive amounts of research on builds, mechanics, etc. I’m really hoping a vet on these forums can help me design a build that revolves around fast dual-wield melee attacks that lifesteal. I’d preferably like it to rely heavily on procs from LMB attacks. If you’ve played GW2, think dagger necro w/ blood tree. Does such a build exist? I’ve been thinking of trying it as a Witch Hunter.

At first, I thought I’d try a chaos/vit WH build, but I was advised that such a build just doesn’t cut the mustard. As such, I’m wondering if I could pull it off by going acid/poison. I thought about maybe this: http://grimcalc.com/build/lIAhYD

However, I’m not sure if all the procs from the dual-wield tree will be enough damage, even paired with shadow strike’s poison modifier. I chose Sigil of Consumption primarily for the heal and the fact that it fits the “vampiric” motif for which I’m shooting. Also a lot of the acid/poison modifiers in the build seem to off-handedly modify Vit damage. Should I trade that out for something else? Is it true that most/all of the lifesteal in this game comes from gear/devotions? Should I consider pairing Nightblade w/ a different mastery?

Anyway, I realize this is all over the place, but if anyone could help me design a melee dual-wield vampiric class, I’d really appreciate it.

http://www.grimdawn.com/forums/showthread.php?t=29617

http://www.grimdawn.com/forums/showthread.php?t=39553