Lulu
Onion Knight
Venus Crest
Time to do a little planewalking! Travel back to Guadosalam, where you'll find some hidden commentary. Return to the Farplane, where you'll see a treasure chest lying around in the southwest portion of the platform.
Venus Sigil
To get this item, you have to evade lightning by pressing X on the Thunder Plains 200 times in a row without being hit. This is quite a feat... But I found a really good hotspot, that will help quite a bit. First, return to Thunder Plains via airship, and walk to the north. When you get to the area with the save sphere, walk a little to the southwest, by the character. Walk in between the two small crater-like impressions over and over again to find lots of lightning that comes in a pretty even schedule. If you do this for a minute or so and it doesn't happen, walk east-southeast to the other cactuar stone. Once you're striked once from there, go back to the other cactuar stone, and the lightning should start striking. Once you get away 200 times, return to the Bilghen Memorial Travel Agency, go inside, the come back out and open the chest revealing this sigil.
The Doll
Now return to Baaj Temple (Airship Coordinates: X: 15 Y: 60) and dive underwater. Swim towards the doors to the north and defeat Geosgaeno. The best way to get rid of this menace is by equipping your party with armor bearing protection against petrification and death. Cast Hastega and Protect on the party, and be sure to use everyone's Overdrives, even the aeons'. After that, search the southern part of the circular underwater area to find a treasure chest containing the little knight.
Rikku
Godhand
Mercury Crest
Okay, from the start of the Sanubia Desert, go up and exit that area to the one with two new exits. Go through either one to arrive in the area containing the Crest. But for now, go ahead and take the left one. After arriving in the next area, be sure and hug the wall northwards. You will find a weird secluded section of the desert that holds the treasure chest that contains the Mercury Crest.
Mercury Sigil
You need to complete the Village of the Cactuars subquest before you can get this. Once you finish it, you'll find the Sigil in a treasure chest in the now revealed Cactuar Village (a sandstorm used to hide it) in the Sanubia Desert. (For more info on the Cactuar sidequest, check out the "Cactuar Village" section of my site)
The Glove
Return to the airship and enter the password "GODHAND" to open a secret location at Mushroom Rock. Go there and then move north to the end of this ravine. Use the Celestial Mirror on the symbol embedded in the rock face to reveal the weapon.