OK, I successfully multiplied the 18 Earth Mallets into 99 with the W-Item trick.

The Zeidrich actually came in handy when fighting Emerald Weapon, since I didn't want to overload the party with materia anyway.

And if you must know why, it stemmed from previous play throughs of FFVII where I wasn't able to get Pandora's Box on the first Dragon Zombie and wasted hours trying to get other Dragon Zombies to cast it. Once I found out that only the first encounter mattered, I decided to start a new game from the beginning but this time try to get everything. About the only items I'm not bothering to get are the Umbrella and Flayer (I'm just not into Speed Square).

Thanks for all your help.