Path of Terraria has several unique items that have set affixes with roll ranges and some have special Alt Use effects
Unique pieces of gear inherit from a base type of another gear piece. For example the Fire Starter bases from Wooden Sword so it inherits the stats from Wooden Sword but has a set list of affixes and has a unique alt use ability.
Fire Starter - Wooden Sword
Blood Oath -
Corrupted Battleaxe -
Guardian Angel -
Bloodclotter -
Rottenbone -
Burning Red Boots