From the official Strategy Guide ...
Leveling Spot # 3:
Eden - Leviathan Plaza
Spot Details:
The Adamantoise offers some of the best rewards in the entire game: 40,000 CP, a Platinum Ingot as its normal drop (sell price 150,000 Gil), and a Trapezohedron as its rare drop. The latter component has a resale price of only 10,000 Gil, but is essential to create "ultimate" weapons and costs a massive 2,000,000 to buy.
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In addition to "premium" components that are designed purely to be sold, there are several standard components with a Gil value that far eclipses EXP or multiplier increases that may offer during weapon or accesory upgrades. Acquiring these can be a great way to generate funds for purchases.
Name Sale Price (Gil)
Gloomstalk 1,000
Sunpetal 1,000
Moonblossom Seed 6,000
Starblossom Seed 13,000
Succulent Fruit 1,750
Malodorous Fruit 4,000
Green Needle 3,500
Perfume 12,500
Two of the best weapon components you can buy (cheap and effective) are Sturdy Bone (80 Gil) and Superconductor (840 Gil).
All you have to do is continuously pour Sturdy Bones into your weapon, until it tells you that you have a 3x bonus (should take at least a couple dozen). When this happens, pour as many Superconductors as you can afford into that weapon. This is effectively the best strategy for turning Gil into weapon levels, and it worked great for me.
The general stradegy is to add organic components (indicated by the claw icon) to the weapon to add to its bonus multiplier. Once the multiplier reaches its maximum (x3), add a bunch of mechanical components (indicated by the bolt icon) at once. This will empty the bonus multiplier, but boost the experience of your weapon significantly. Thus, if you have a few particle accelerators lying around, you can use those in place of superconductors.
If you're lucky, the weapon's level will be replaced with a star. When this happens, you'll need a special item to upgrade it to its next form. Most of these items can be purchased at The Mother Lode. This upgrade will allow you to continue levelling the weapon. Note that each weapon can be upgraded twice - once around level 26 (different weapons take different catalysts at this stage), and again at around level 61 (this always takes a Trapezohedron).
All in all, you won't need anything more than a level 61 (starred) weapon to complete the story missions of the game, but if you want to get all the final weapons, you'll need six Trapezohedrons, which cost around 2,000,000 Gil each. See other guides for best places to farm Gil and rare components.
Best Answer
It is most likely a Red Herring in relation to the Treasure Hunter Achievement/Trophy.
the description reads (at least on the PS3)
and this guide on gamefaqs says
Now, according to this guide, the Shield Talisman has a Max Level of 2 but no Transformation Cataltst, much like some of the other Talismans.
Also, even if you have completed your inventory you have to go to see Bhakti in Oerba to actually get it as noted in my first link,
as such while trying to get the Treasure Hunter Achievement/Trophy by having some accessories which can go up to Level 2 and not getting the Achievement/Trophy until you see Bhakti the player can be tricked in thinking that they are missing a Transformation Cataltst meant for Talismans when this isn't the case.
As for djsmiley2k's comment, this guide (G0900) says it's only worth if you dismantle started accessories and weapons (Max Level)
which for the Shield Talisman you get
weather they are any good to you or not is up to you however alot of the Gil Farming Suggestions don't make use of mass producing Max Leveled accessories and weapons and Selling them or their dismantled components (most are strait farming and selling off enemy drops which you could get from dismantling but be more efficent to get as drops)