To resolve the knife bug (pc version) there is another solution... Search the file "Assassin4.ini" and Enable a keymap for use the Dpad.... Open Assassin4.ini (notepad) and search for:
....
[KeyboardMouse2 DefaultBindings]
...
PadUp=-1
PadRight=-1
PadDown=-1
PadLeft=-1 ....
....
[KeyboardMouse2 DefaultBindings]
...
PadUp=-1
PadRight=-1
PadDown=-1
PadLeft=-1
....
By default the -1 is for disable ... change in:
PadUp=12
PadRight=27
PadDown=26
PadLeft=25
PadUp=12
PadRight=27
PadDown=26
PadLeft=25
(...)
12 is Keyboard key "?"
27 is keyboard key "+"
26 is keyboard key "è"
25 is keyboard key "p"
In game can use the keyboard for emulate the Dpad and select the knife...
(the assassin4.ini file is under documents in Assassin IV Black Flag directory)
