When using the new talent Shimmer Strike with a dual weapon, using any of the heavy attacks for the initial infiltrated strike causes you to leave stealth immediately rather than get the 3 sec additional stealth. The heavy strikes of any other weapon or the light attacks of the dual weapons grants 3 sec of stealth as described. I have no proof but it looks like it has to do with the 2 hits in a single attack, however, since a dual heavy does not expend both instances of infiltrate when using Cloak of Pain, I’d guess it’s unintended.
EDIT: Ok, so we got that from testing it in the keep on dummies after a friend experienced some difficulty with it in a match. But the behavior with dummies appears to be different from actual enemies (for starters, you can’t kill them to proc the talent). In the match it still feels weird, the time you get when using dual weapons "felt " shorter than with single weapons but you do go into stealth at least.