This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
It is possible to defeat Hammer during disc 2 without running away. To
do so, turn on your boosters during the battle, and try & keep your
gears at attack level 3 as much as possible. When Hammer starts to
flash, each gear only gets 3-4 turns before Hammer self destructs. Now
is the time to pummel him using level 3 attacks. Weltall-2 should use
System Id immediately and keep using its Goten X attack against Hammer.
If you manage to defeat Hammer, you'll get the Trader Card, a powerful
accessory which increases the chance that rare items will appear.
Here's a few ideas on what to do with the Trader Card:
* Equip it immediately on a character after Alpha Weltall crushes Fei on
board Mahannon, but before fighting Ramsus and Miang inside Merkava.
With the Trader Card equipped, Omiomorph (Miang's gear) will drop an
ExecutionerGown, the best armor in the game for Maria/Emeralda/Chu-Chu.
* Equip it in the Sandman Desert. The dragons that roam around the area
drop some amazing equipment when defeated, including Citan's best sword.
* Equip it in the forest around Taura's House. Some of the monsters here
will drop shoes that automatically casts "Goddess Wake" on the wearer at
the beginning of battle. It also puts the wearer's gear into a permanent
booster mode with no additional fuel loss during gear combat!