Ok, it's easy to down something so to put a little perspective on this. The Dual Wield (DW) patch came out back in EoF (T7) days. My guild at the time was a casual raiding guild (never beat Rumbler or could clear MMIS) so all of my gear was instance gear. My
only raid piece of gear was Qeynos Claymore.
When the DW patch came out we were raiding Emerald Halls that day. With the WIS spec on I was parsing in the 900s consistently. During the raid I used my Free Respecs and spec'd to a DW DPS spec. After that (the very next mob and beyond) I was parsing 2700 - with Claymore and that legendary Bloodspiller from Unrest. I went from the bottom of (or not on) the parse to the top of the parse. Assassin respec'd immediately after the raid.
You don't lose any soloability dumping the WIS build and going with the DW DPS build. When I solo, I don't take breaks between mobs - not even to wait for CAs. (even if all are down) Each fight is 10s or less. The more dps you do, the easier it is to solo. Not to mention Walk the Plank is HEAVENLY!
Start off with this and work up:
First 5 AA
..............4pts into AGI, 1pt into Walk the Plank (WTP)
Next 5 AA
..............4pts into INT, 1pt into Boot Dagger
Now max out WTP and proceed down the AGI line till you finish it. Then work on the STR line. When this tree is complete than you can start the weak sauce Swashy Tree.
Solo Combo:
Brazen (sneak attack + Stun), 2 back attacks, Cheap Shot (mob should still have his back turned), your triple attack, double attack, (mob is probably facing you now) so Eye Pokey thing, nuke the snot out of it till Brazen is back. When Brazen (ur sneak attack + Stun) is back, hit your WTP to turn mob, Boot Dagger to go invis, Brazen to stun his ass, back attacks if they're up and finish the stupid thing off.
If the mob still has health after all that you must be going after a Triple Up.
Do it right and you'll barely get touched. Stun lock FTMFW! Screw that wimpy WIS spec.