How does ezio gain life levels in assassins creed brotherhood

The best way to increase Ezio's health is to buy armor from blacksmiths. There are 5 armors in the base game and each have different tiers meaning the higher quality armor increases Ezio health more than the lower quality armor. Below I have listed all the armors and when they become available. (Weakest to Strongest)

Roman Armor - Full Set available after Sequence 05 - Total Cost 5500 florins

Rondelle Armor - Full Set available after sequence 06 - Total Cost 17100 florins

Plate Armor - Full Set available after sequence 07 - Total Cost 31600 florins

Suesenhofer Armor - Full Set available after sequence 07 and completion of the shop quest "Exotica" - Total Cost 23200 florins

Armor of Brutus - Full Set available after completion of all 6 Lairs of Romulus - Total Cost 0 florins (completely free if you don't mind dungeon crawling)