In Assassin's Creed II, which Renaissance inventor designs Ezio's hidden-blade upgrades?

In Assassin's Creed II, Leonardo da Vinci designs Ezio's hidden-blade upgrades.

Leonardo is one of Ezio Auditore's most important allies in the 2009 game. After Ezio brings him pages from Altaïr's Codex, Leonardo studies the diagrams and uses his engineering skill to improve Ezio's equipment. His work enables upgrades including the poison blade and the ability to use a second hidden blade.

The game presents Leonardo as a gifted Renaissance inventor while also making him part of the fictional Assassin storyline. Ezio repeatedly visits him as Leonardo moves from Florence to Venice and later to other locations. The relationship gives historical context to the technology without claiming that the real Leonardo built Assassin weapons.

Michelangelo and Sandro Botticelli were genuine Renaissance artists, but neither serves as Ezio's engineer. Galileo lived later, becoming prominent in the scientific revolution of the seventeenth century. Leonardo is the specific historical figure connected to Ezio's equipment development in Assassin's Creed II.