Deffinately an interesting concept, but I managed to come up with some flaws:
1) Too energy intensive, if you get struck with an energy denial mesmer or an energy draining enviromental effect, you're buggered.
2) Virulence, whilst good for pve, causes disease, which if you're facing a different species can be good, but if you're facing humans, you are once again buggered since you are in melee range, and you're going to catch it. Making this build useless in PvP since you'll probably infect your own team, and useful in PvE as long as it isnt against Humans.
But I do like the idea of this build, and it could be very effective if used right with some tweaking.
ehm.. energy intensive and if you get struck by a energy denial mesmer etc. you are buggered? ofc.. but why would a mesmer care about a sin? and besides, there are lot of other counters...
anyway.. looks cool.. but as stated above.. disease can make it quite dangerous to use in pvp