Thorald Upgrades
From Sons of Valhalla Official Wiki
Thorald can have its stats and equipment upgraded at various buildings. Unlike unit upgrades these will carry between levels and do not require the buildings themselves to be upgraded to purchase. All upgrades cost Gold.
Mead Hall upgrades
The following upgrades can be purchased at the Mead Hall.
Blacksmith upgrades
The following upgrades can be purchased at the Blacksmith.