An Israelite Assassin during the Jewish Revolt against the Roman Empire. The Sicarii (Latin for "dagger-men") were an extremist splinter-group of the Jewish Zealots, who attempted to expel the Romans, Herodians, and their partisans from the Levant.
The prayer shawl is called a tallit - normally it is only worn during Yom Kippur and morning prayers, but these Assassins were highly religious, and might have worn it a lot more than that - perhaps inspiring later Assassin hoods. The spear is actually a Hidden Blade itself - when retracted, it would appear to be a shepherd's staff or the like.
DISCLAIMER: This design is probably apocryphal - the biblical tallit was more akin to a mantle, or poncho, and only developed into the version seen here in 1000 CE.