When Skullius first created [Infinite Sword God] by combining a collection of skills, its unique, compound nature – how it had multiple sword styles packed into it – had prompted the guidance field to advise Skullius to make it into a Hidden Class.
(A/N: Refer to Ch.991)
The Hybrid Warmoth, after learning that that was still an option for the skill an hour ago with his alter memories, had immediately decided that [Infinite Sword God: Primordial Sword] would work better in the hands of Pherdanta.
Before, when the Unlimited Stars were simply the Unlimited, she had been the only one to not have a Hidden Class. Hers was an Advanced Swordsman Class that allowed her to seamlessly merge two or more swords to create a single, unique one provided that she fully understood the properties of all the swords. The Class also had the added quirk that made living things oblivious to Pherdanta's existence until she interacted with them.