Urth's Fount Extreme - Gilgamesh Extreme
These two fights were some of the most disappointing to me... i.e. Urths Fount and Big Keep.
Granted we aren't necessarily done with Gilgamesh... but I can't help but recall that 8 armed pick with 8 weapons, and the wild speculation that we'd be able to challenge for weapons drops... perhaps even with a risk of losing your weapon.
Likewise, Odin was a pushover. I would have loved to see something more... perhaps having to kill him multiple times, and at different times he possesses a member of your party who you then have to fight an Odinized version of...
In any case.. There's so much more that could have been had... Would have loved a challenge. Would very much like Extreme Versions... even if the drops are purely glamour.