Virtuoso shatters need to be unblockable, independent of view direction and either instant cast/faster projectile speed or somehow make up for being so slow to even be remotely usable. Also, please give either Virtuoso or (better) core Mesmer 25% movespeed. Mesmer and Guardian are the only classes to not have some way to achieve this without having to sacrifice their runes, with Guardian having access to it on 2 elite specs compared to only Chrono for Mesmer + everything else that guardian has going on for it right now.
Additionally, and since you seem to want to go in that direction, change Virtuoso to be more of a ranged DPS, by: Stocking blades automatically, both in and out of combat, adding ammo to every shatter, except maybe F4. This way, we can actually stay at range and might, at long last, actually have some form of sustained damage.