How do you get a bow in assassins creed

I'm told in Assasins Creed (the original) you can unlock a crossbow after collecting all the flags and killing all the Templars. I have not done this myself, so I'm not sure if this is entirely true.

In Assassins Creed 2 you can access your hidden gun by pressing and holding "R bumber" then selecting it from the top right of your weapons wheel.