The character makes an items aura register to detection
spells (and similar spells) as though it were either a magic item
of the type that the character specifies or the subject of a
spell that the character specifies. The character could make an
ordinary sword register as a +2 vorpal sword as far as magical
detection is concerned or make a +2 vorpal sword register as if
it were a +1 sword.
If the object bearing Nystuls magic aura has identify
cast on it or is similarly examined, the examiner recognizes that
the aura is false and detects the objects actual qualities
if he succeeds at a Will save. Otherwise, he believes the aura
and no amount of testing reveals what the true magic is.
If the targeted items own aura is exceptionally powerful
(if it is an artifact, for instance), Nystuls magic aura
Note: A magic weapon, shield, or suit of armor must be a
masterwork item, so a sword of average make, for example, looks
suspicious if it has a magical aura.