I finished it 100%. Took me a little bit of time but it was really fun, and a bit of a challenge sometimes.
~ All Challenges @ 3 Sigils (therefore all Secret Reports unlocked)
~ All Mission Mode missions finished, with a total of 358 Mission Crowns obtained
~ Achieved Lv. 100 (this was the worst)
~ All items synthesized, as well as bought
~ All Moogle Freebies obtained through redemption
I think my total gameplay time was something around 90 hours.
Such a great game, and mastering it was definitely something I had to take up (along with the rest of the KH series).
Ultima Weapon is just an ability panel that takes up one spot on the grid. It adds 15 attack power to any weapon you have equipped.