[@ShidenBlades]

For example...

For your magic aura sensing this is assuming that A) an aura is present on the characters abilities B) that the aura itself is not altered in any fashion.

For the illusion one, it would be possible to construct an illusion that could fool that. I'm merely pointing out that there are methods of construction with magic that would allow this. Right now, it states with absolute authority that it can identify illusions. I'm generally not fond of language that states things with absolute authority as there are clever constructions of abilities that would allow this to be rendered useless even if said ability would technically fall under the purview of the item.

Does that make sense?