Since Jayce had easily applied Limitless to his spell, Bella gave him the okay to use it on one of his sensory spells. Jayce chose [Dark Sense] as it was of lower rank, making him assume it would be easier to practice.
[Dark Sense (D) has been activated]
[Augmentation (A) has been activated]
[Dark Sense (D) has been augmented]
[Dark Sense (D)]
{The darkness is your greatest ally. You are able to extend your senses to the surrounding shadows, picking up on beings and objects from a distance away. The amount of detail received and the distance it can be applied to is dependent on the skill's rank.}
[Additional Effects:]
[Sense Improvement]
{You are now able to distinctively sense the shadows of other living beings.}
It was a simple improvement to the spell was a good one nonetheless. Although not implied in the description of the spell, Jayce wasn't able to sense shadows belonging to living beings.