Unused infusion
Sure Strike
Unused. It has no effect text and nothing in the game can take it.
How you get it
No perk sells it, and you can't add it at the anvil.
Infusions
What every infusion does, the perk that unlocks it and what it goes on
Data from build 25583279, updated
14 of the 19 infusions are bought as a perk first. Blacksmithing perks add theirs at the anvil, Cooking perks add theirs at the stove, and Quality Crafting covers furniture. Chase Loveable first: a Loveable dish counts as a loved gift for every villager. The fire, ice and venom sword effects aren’t forged at all.