In Assassin's Creed II, which Renaissance artist helps Ezio Auditore modify his hidden blade?

In Assassin's Creed II, Leonardo da Vinci helps Ezio Auditore modify his hidden blade.

Leonardo is introduced as a close friend of Ezio's family in Florence. After Ezio inherits Altaïr Ibn-La'Ahad's codex pages and hidden blade, Leonardo studies the designs and makes the weapon usable without requiring the missing finger described in the original Assassin order tradition.

The game presents Leonardo as an inventor and interpreter of the codex, not as an Assassin himself. He also helps Ezio understand several codex pages and creates equipment used during the story. The character is fictionalized, but the real Leonardo lived from 1452 to 1519 and was active in Florence and Milan.

Players sometimes confuse Leonardo's role with that of Lorenzo de' Medici or Niccolò Machiavelli, who are also important historical figures in Ezio's story. Leonardo's distinctive contribution is technical assistance and invention.