Once you arrive at The Haven in Prince of Persia: The Lost Crown, you will be able to start upgrading your gear.
 
The cost and materials needed for an upgrade will depend on the type of gear, and how many times it was already upgraded.
 
To upgrade your gear:
 
•  Talk to The Mage at the Magi Emporium, or talk to Kaheva in Kaheva's Forge.
•  Select "Buy" and choose "Upgrades".
•  Locate the upgrade from the list and select "Upgrade".
•  Select "Yes" to confirm.
 
From here you can upgrade the following gear:
 
Amulets can be upgraded in Kaheva's Forge to make them more powerful.
 
Amulet holders can be found by exploring mount Qaf, or bought at the Magi Emporium.
 
Bow and chakram can be upgraded in Kaheva's Forge.
 
Potions can be upgraded, increasing the number of potions you can hold and how effective they are.
 
Qays & Layla are the dual swords of the prince. They can be upgraded in Kaheva's Forge to deal more damage.
 
Some upgrades will require Azure Damascus Ingots. They can be found by exploring mount Qaf, by opening chests and completing quests.