how do u upgrade your armor?

By:

- Finding, buying, or having better armor crafted.
- Inserting rune stones into the slots that appear on some armor/weapons.
- Visiting blacksmith areas and using the armorer's table/sharpening stone.
- All custom made witcher armor and weapons can be upgraded once you have found the schematic diagram in one of the witcher treasure hunts and then found the appropriate blacksmith/armorer with enough skill to do the upgrade. There are 4 levels of upgrading, the base level, then "enhanced", "superior", and "mastercrafted", each giving better base level and magic enhancements as well as including additional slots for runes sometimes. The higher level upgrades require Geralt to be a higher level to use however as well.

For witcher school armor (Cat (light armor), Griffin (medium armor), Bear (heavy armor) ) - you can find scheme for 3 step upgrades.