The type of material needed depends on the item you'd like to upgrade as well as the upgrade level. Each item can be upgraded 9 times (quiver and tool pouch 4 times). The maximum item level is 10 (5 for the quiver and tool pouch). The higher the level, the more crafting materials are required. However, the item level cannot be increased beyond Bayek's level. This means you won't be able to reach maximum item level before Bayek himself reaches level 10.
Upgrading these items will boost their effects: melee damage, ranged damage, health. For the quiver and the tool pouch, upgrades increase their capacity.
If you have any questions, feel free to contact us!