I've gotten as far as Venice, and I haven't had much difficulty with any of the fights so far. The one thing that seems particularly dangerous is the heavily armored knight-type guards. What I have found to work:
- 2 Throwing knives take one down, provided you have room and time to throw effectively.
- Button-mashing hidden blade attacks also kill them, as they can't recover and counter between those quick attacks.
However, they usually show up in a group of guards, and both of these options leave me open to other attackers. It's also hard to ignore the heavies and kill off the others, because I can't defend against their attacks (this also disables my counterattack, though I can still dodge).
Is there any surefire quick-kill method for these guys (when they're among a group)? Should I just resign myself to running around like a ninny, slowly poking them to death?