This is a story-related trophy and cannot be missed via normal campaign progression.
At one point you will be escorting Leonardo to Venice. You will take over the carriage and have to swerve on the narrow mountainside road to avoid hitting either a wall or somewhat inconveniently placed debris. Soldiers will jump onto the back end of the carriage so you either need to hit the back end of the carriage against a wall to scrape them off or swerve side to side violently when the reach the top.
Try to avoid the fire arrows as best as you can. Eventually you will jump off the carriage to fight some soldiers. I took the easy route and chucked a smoke-bomb at my feet when the got close and killed about 6 of them before they raised a weapon. After killing all soldiers, head to the marker to enter Venice. The trophy will unlock during the ensuing cutscene.