Nidhögg the Bleeding

If you bleed, your foes are sure to do so as well.
Overview

Because the enchantment replaces the base sword’s progression, it resets any existing upgrades on the normal weapon. Its damage and durability improve with quality upgrades, but its current practical ceiling is limited by available materials and progression. As of patch 218.15, the highest obtainable upgrade is level 2.
- Quality 1: 135 slash damage, 200 durability, costs 1 Nidhögg, 6
Flametal, and 1
Bloodstone
- Quality 2: 141 slash damage, 250 durability, costs 6 Flametal and 1 Bloodstone
- Quality 3: 147 slash damage, 300 durability, costs 12 Flametal and 2 Bloodstone
- Quality 4: 153 slash damage, 350 durability, costs 18 Flametal and 3 Bloodstones
The total cost for a fully upgraded sword is 1 Nidhögg, 42 Flametal, and 6 Bloodstones. Since the enchantment removes prior upgrades from the base sword, it is best treated as a separate investment rather than a direct improvement path from an already enhanced Nidhögg.
Official description
If you bleed, your foes are sure to do so as well.