Not that anyone really cares but I have been replaying through FF X recently and I figured out what one of the key items I'm missing is. The fourth one in the right hand column is the rusty sword. It disappears after you use it so that's why I don't have it anymore. Still kinda curious about the other item though...
EDIT:
It's the Cloudy Mirror, it transforms in to that other item when you power it up.
Yah all my questions got answered! :)
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They call me Gato, I have metal joints, beat me up and earn 15 silver points!