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.
There are two secret fighters available in this game, but unlocking them
takes quite a bit of work:
To get the "Unknown Fighter Type 1," find any 15 special bonuses. It
doesn't acquire gunpods like the other Einhanders acquire them. Instead,
weapons are powered up by collecting gunpods - if you've played "UN
Squadron" by Capcom, the system will be very familiar to you. For every
five gunpods received, the ship's machine guns are upgraded. Each gunpod
also has a special effect; try them all for a myriad of various
The "Unknown Fighter Type 2" is awarded to the gamer who finishes the
game on the highest difficulty level using only one or two continues.
It's like an Astraea, but has 9999 ammo on all gunpods!