User blog comment:SupremeAssassin/Assassin's Creed 3: Combat System/@comment-4013467-20120527154224/@comment-4115686-20120527201931

I figured out how to use the Poison Blade in AC2.

Situation: There's a bank guarded by 4 guards. There's a patrol nearby. When the patrol gets close enough, you poison the guard in the back. Then you back away, wait, and then bank guards will go watch.

Then, you sneak into the bank, steal the money, and leave without getting noticed.

I like it because it's a fifth method of getting into restricted areas (first three are the various groups, the fourth being combat).