Two weapons means 1200 life on hit just from sockets. Tack on the Dex/Vit/LifeonHit from your paired weapons, alongside the additional DPS, and suddenly you're some kind of crazy vampiric killing machine. Apparently.
I just realized that Amethysts start to kick the crap out of every other gem at higher levels. Thought it'd be minor gains like Flawless Square, which only adds 65 Life on Hit (almost meaningless). I WAS PROVEN WRONG. Even just Star Amethysts, naturally craftable by leveling your Jewelcrafter, net you 300 LoH EACH! Holy !@#$. Am I the slow one here? Or has no one else tried this out yet?