F1 to F3 :
Cast time made shatters feel clunky, making it not flow well with the skills.
Also as a master of blades, Virtuoso should be able to execute their blades with grace instead of "Give me 1/2 to 3/4 sec to throw my dagger stacks...".
With the cast time in place, it is just ungraceful.
Rain of Swords :
The pulse damage does not reflect the skill name & animation. The damage from this skill should be more rapid (think ranger's longbow 2). The slow pulsing damage and low damage per pulse make this skill laughable and easily avoided without much consequences. Instead of a 5 pulse damage why not make it damage rapidly (x10~x20) at lower damage per tick, so that it feels more like "Rain of Swords" instead of "Pulse of Swords".
Jagged Mind :
A poor designed trait to incentivized condition build when most of the condition damaging weapons and utilities do not use "Blade" to trigger this. The only "Blade" are the F1-3, Psionic, Dagger 1-3, Greatsword 2-4, Which means those are the only skill benefitting from the trait itself and of all the mentioned ones only F1-F2 benefit most from it. The lack of synergy of this trait with weapons skills, utilities and other core traits is just bad.
Other feedback and suggestions :
Condition traits on Virtuoso currently is not even worth taking, considering Mirage does a better job. These traits are better off converted into traits that benefit Virtuoso's Psionics & Weapon Skills which isn't available in Core Mesmer Traitlines.
F1-3 & Thousand Cuts are projectiles without Projectile Finisher and yet gets punished by reflects. The lack of counter play as the Virtuoso is sad.
Illusion related traits and floating dagger should be updated. Gaining floating dagger should be considered as summoning illusion.
Bountiful Blades trait can be rework to benefit not just Greatsword in general, since the name is about blade why not make it also benefit blade related skills.