The Hidden Blade Assassin's Creed in Depth

Equestrian-Assisted Blitz Assassination
This isn't the fastest way to kill Stefano. But it sure is fun. Dismount over the disguised guards to avoid detection. One guard was bowled over by the horse during the dismount. Since Ezio wasn't on the horse at the time of the collision, he remains Anonymous afterward.

Blitz Assassination
Once inside, continue to run quickly and keep your distance from disguised guards.

Adding Insult to Injury
Take his money. Then kill him.

Haystack Assassination
Stefano ordinarily walks around under the sheltered parts in a pattern. If he sees you at all, he'll stop walking altogether... unless he sees a dead body. Wait for Stefano to leave the area around the haystack, and then trigger a fight with the disguised guards. Stefano will see the fighting from a distance, but he won't be alerted enough to flee. When the guards are dead, jump in the haystack and wait for him to inspect the dead bodies. He should approach closely enough for an assassination from the haystack.

Waypoint Separation
Please watch this video on Waypoint Separation if you are unfamiliar with the concept:
http://www.youtube.com/watch?v=Qo2lTyCD3GM
If you become Exposed to Stefano, he will try to flee to the abbey. This is his waypoint. Clear the area of guards, so you can grab Stefano and go on a small trip. I wrapped a rubber band around my controller to pull up on the left stick, so I could put the controller down and do other things. 3-4 minutes later, we're so far away from the abbey that the waypoint isn't modeled in the game anymore. With nowhere to go, Stefano is immobilized.

Air Assassinations
Stefano likes to stay under the sheltered areas, but he'll come out into the open if you leave a dead body there for him to inspect. I prefer the appearance of the air assassination animation when it is night.

Double Jump Assassination
Climb to the upper roof and line yourself up with the dormer on the lower roof. After each jump, be sure to keep pushing up on the left stick to land with a roll.

Throwing Knives
For a silent kill and a clean getaway, use throwing knives from the roof. Lock on and throw 3 knives. Only 2 knives are needed to kill Stefano, but the second knife does not reliably hit the target since he gets knocked back after the first knife.

Stunt Assassination
Lure Stefano outside with a trail of dead bodies. Position one of the dead bodies at the appropriate distance from the stunt tower. Climb up and trigger Stefano's movement. (You'll hear, "Let us pray..."). Leap when he inspects the positioned body.