Bloodgeon

The blood all but soaks into this mace, and it always yearns for more.
Overview
Bloodgeon is an enchanted version of the normal berserker axes. It deals extra damage based on the player’s missing health, so the lower the player’s health is, the stronger the bonus becomes. The bonus increases by 0.2% per missing health point, and the enchantment also resets any previous upgrades on the normal axes.
It is a high-risk weapon that rewards fighting while injured, making it unlike most melee weapons in Valheim. Because its damage bonus depends on lost health rather than total health, it is strongest when the player deliberately stays below maximum health, but that also leaves much less room for error.
- Quality 1 to 4 blunt damage: 135 / 141 / 147 / 153
- Quality 1 to 4 durability: 150 / 200 / 250 / 300
- The damage bonus is tied to missing health and remains the same across all qualities.
To unlock the recipe, the required crafting materials must have been in the inventory at least once. The weapon upgrades through additional 

Official description
The blood all but soaks into this mace, and it always yearns for more.