This isn't actually Mesmer specific, but I did notice it while playing my Mesmer and it definitely relates to my most recent weapon selection that I guess would be considered largely unorthodox. Just the other day I was experimenting with (S/S S/T). As I implied above I'm sure most people would think this is really odd. Partially it’s because I can't fully decide which offhand I like better, but more importantly this reasoning has to do with me really focusing on power and crit damage therefore the scepter is God awful in my opinion. The torch is just lovely and I’ve been using it as an offhand primarily all the way to 60. The Prestige truly is a skill of wonder and thanks to traits both my torch skills remove conditions from myself. Though the combo of (S/S S/T) has a number of problems as you can imagine: one being that I have almost no range capability which is extraordinarily dangerous for a LA class, and then it also sucks because when I do swap weapons my main hand sword CDs remains where they were... I guess I understand why because this would allow me to almost spam certain skills, most significantly, Blurred Frenzy, let’s be honest that's just unfair. However, I also don't understand because I'm making the choice to limit my own versatility and ranged capability as I mentioned to have duplicated slotted weapons. On top of that, it's physically a different sword... If other weapon cooldowns aren't carried over by slot skill why shouldn’t it the same weapon type be any different?

Anyway, I'm still going to play around with it a bit. My sword cooldowns are pretty short anyways and I'm looking at toying with a few different mantras currently that would basically give me something to do while I'm being not ranged and waiting for CD's. I donno, we shall see.. I just thought it was interesting.
Sidenote: Mesmer’s should have one more main hand choice. Dagger, Mace, Pistol…..