The RAW for the Opportune Parry deed seems to indicate that a swashbuckler can parry an incorporeal attack, such as a ghost's Corrupting touch, even with a non-magical weapon.
Considering this kind of attack is a contact attack, ignore all corporeal defenses, and considering that ghosts ignore non-magical weapons, I find it a bit problematic.
Is there something in RAW that I am missing, that would prevent a swashbuckler from parrying an incorporeal attack, or at least make it more difficult?
So, Parrying is an attack (based on the fact that it requires an attack roll), and the incorporeal creature is immune to nonmagical attacks. Therefore, RAW seems to be that a nonmagical weapon could not successfully parry an incorporeal attack.
A Parry, however, does not harm the creature, so so a magic weapon would seem to have a 50% chance of parrying.