Crossbowmen are guards armed with crossbows featured in Assassin's Creed: Brotherhood. They patrol and defend the rooftops similar to the archers, and are thus able to catch sight of Ezio from a distance. However, unlike archers who draw their swords if Ezio comes too close, they instead also use their crossbows for melee combat, and will still fire a bolt at Ezio even at close range.
Crossbowmen can be an annoyance particularly when encountered in groups, as crossbow bolts move faster than normal arrows, and will easily hinder rooftop travel by causing Ezio to fall and take damage. Crossbowmen are skilled marksmen, and are capable of damaging armor with their shots.
When investigating the sight of an assassin (seeing Ezio before the SSI filling red) the crossbowmen try to follow him, therefore stealth and/or a quick killing weapon (ie: crossbow) is recommended to avoid a fight and diminish the chances of falling from the roof and bringing attention to yourself.
Trivia
Though the crossbows used by Crossbowmen seem identical to those used by Ezio Auditore, they can't Concept Art of the Crossbowmanbe picked up after the Crossbowmen drop them and will disappear soon after the camera loses sight of them.
While looting Crossbowmens corpses, occasionally, bullets can be found.
