The Immortal Sword series consists of large, themed swords in the catalog that are worn as back accessories. It is one of the longest ongoing series of items on Roblox. Each item has the term "Immortal Sword" in its name, along with a unique title. These swords are usually sold as limited unique and only have 100 copies available (with some exceptions). Finally, the description will always consist of the following phrase at the end:
"This sword hangs on your back, so it's always ready for action. It's a hat though... so it's never really ready for action."