Quick Question About AC2 Double Blades

How do you use them? I unlocked double blades but I can only kill one guard when there are two of them, Do I have to upgrade them, or have I not unlocked them yet?

actually sneaking is easy once you get the hang of it, guard only see you from the front, and you can sneak in groups of people or creating a diversiondoubalfa

I haven't quite mastered the fighting and assassination controls so sometimes the things I try work and sometimes they don't. In order to do a double assassination you just have to be looking at one of the two guards. Don't lock on to one of them though because it will just kill the one you've locked onto. When you look at one of them without locking on there should be an assassination option on your control HUD. Once you press it he will take out both of them.