Unique Binding Factors are… well, unique.
As such, if one paid enough attention, they could detect the signature of the spell creator within their spell. But because, despite uniqueness, characteristics are usually common, nothing especially different or attention-grabbing is felt and all signatures are usually ignored.
That was not what Kerwin felt from Caius's spell circle. He felt like the mind that conceived it didn't belong in this world, hence the otherworldliness, and it filled him with a sense of anxiety.
During his spell cast, Caius noticed the expression but didn't quite understand it. He didn't think he had done anything special. He had simply cast one of the spells he had spent his time creating since he discovered his Unique Binding Factor.
