Why Is It Called Virtuoso/Bladesong?
ANet, please help me understand why you chose to call this Elite Spec "Virtuoso" and the "new" mechanic "Bladesong". Other than the spec name and mechanic name there doesn't appear to actually be any music/song theme to their kit. There isn't even some sort of base or trait support for bladesongs providing "lingering" effects which is the most basic type of music themed mechanic in MMOs there is. You play against a Chronomancer and see time based magic, you play against a Mirage and see blur/mirage based magic.... you play against a Virtuoso playing his Bladesongs and you get.... mind daggers?
This is a first impression you're going to continue to receive a lot and hopefully something you care about design enough to address.
Blade'songs' Are Worse Than Original Shatters
All of the Bladesong effects are almost exactly the same as the default Shatter effects. The only major difference is the resource that fuels the mechanic. You lose the ability to get Shatter effects with 0 resources (daze/distortion), you lose clones taking hits for you, and you lose the excellent low-clone scaling of Shatters. For example, a 1 clone + Mesmer Mind Wrack deals 71% of a 3 clone Mind Wrack. But F1 Bladesong deals 20% per blade and based on tooltips you need 3 Blades just to match the 1 Clone + Mesmer Mind Wrack. And what do you get in exchange? The ability to stock 5 resources instead of 3 + 1 free?
Besides some minor changes to targeting and delivery method this new mechanic just doesn't really deliver anything other than a cloneless version of shatter that scales poorly.
The Weapon
And finally, spec theme/mechanic aside... if you wanted to make a Mesmer who was all about daggers/blades everywhere then why didn't you at least let us dual wield them? That's hardly an unaccepted practice for elite specs and Mesmers have never received 5 skills from one before. This spec just seems like a handful of ideas glued together with no thought for theme or overall design.