The Hidden Blade Assassin's Creed in Depth

Turn targets into one-hit punching bags!
Read this description for the explanations of how each target was set up, as well as why other targets couldn't be killed this way.

Tamir

You can't take his heath down early without getting detected, which makes it impossible to progress.

Garnier

Get into the hospital early through the window.
http://thehiddenblade.com/garnier-easy-way-preassassination
Then take down his health until he's one punch away from death.

Talal

After killing his guards, take out Talal's health with throwing knives.
http://thehiddenblade.com/air-assassinate-same-height
You'll need to have done the Garnier assassination first to have the knives unlocked.
Now one punch is all you need to take him out, but it's easy to miss on the running target.

William

Get into his fortress early.
http://thehiddenblade.com/williams-instant-kills-and-king-richards-death
After punching him nearly to death start the scene. Afterward sneak up on him with a jump. If you get detected, William will get into combat stance and block the punch, which happened a lot until I jumped from the spot in the video.