This is the only way I know how to assassinate Majd Addin while remaining Anonymous both before and after the kill. The strategy is based on a new exploit I found, which I call the "broken timeline exploit."
When you collect a flag, the game saves its current state, which includes information like which guards you've already killed. If you die later, the game returns you to the flag location and restores the previous state of the game.
The game developers made an interesting exception to this. If you collect a flag during an assassination mission and later die, you do not return to the flag location. Instead, the mission starts all over. But they overlooked something... The game still saves which guards you've killed when you collected that flag.
This video is based on exploiting this developer oversight. I fought and killed everyone besides Majd Addin, and then I collected a flag, which recorded all of their deaths. Then I jumped off a tall building to kill myself. When the assassination mission reloaded, the game faithfully remembered which guards surrounding the execution platform had already been killed... all of them... leaving me alone with Majd Addin.
Some guards in the game do not respond to this exploit because the game spawns them as part of the assassination mission. For example, the guards that William de Montferrat lectures in his office are not susceptible to this exploit. One of the archers north of Majd Addin is also spawned regardless of whether you've killed him previously.
I miss Altair.