The doors of Lisbon Metro not just warn you about leaning but also highlight the risk of being trapped by closing doors. The Martim Moniz station is decorated with knights and one of them is used to illustrate that icon. This station is called after the noble knight who sacrificed himself by lodging himself in the doorway, preventing the defending Moors from fully closing the door of São Jorge Castle.
I consider that is the proper way to interpret history. A bit of humor, may be a bit of sarcasm and that will work out with the national idea!